These are minutes for finding composure, getting "in the zone" - and putting the finishing touches to make-up. The special quality of this period has long fascinated photographer Simon Annand.
For more than 30 years, he's been immortalising it through his lens after being granted exclusive pre-show access into stars' dressing rooms. The result is a series of images called simply The Half.
A forthcoming exhibition from the series will include 74 photographs that have never been seen before in public, with subjects including Phoebe Waller-Bridge, Dame Judi Dench, Helen Mirren, Gillian Anderson and Stephen Fry.
Annand says that unlike working on a film set, where the actor can wait for ages to be called, "the theatre demands that he or she be ready at a fixed time and this is repeated each day. There is no escape and the discipline required is intense".
In his sessions, he's tried to be as non-verbal as possible, so as not to disturb the rhythm of the actor, he tells BBC News, adding: "Objective information can be more revealing, allowing the viewer to read the image as they wish. Rather than an attempt to influence their impression."
Annand has talked us through a selection of shots from the show.
Gillian Anderson at the Young Vic in 2016 for A Streetcar Named Desire by Tennessee Williams
She played the fragile southern belle Blanche Dubois.
Annand: "For this performance she won the Evening Standard award for best actress and made Blanche her own. This session lasted barely four minutes but that was enough.
"Gillian's presence is such that almost anything she does makes a photograph. In this case, turning around, at a moment when she is slipping into the fictional character, suggested to me why she was interested in playing this part.
"It has always been my intention to make images where the atmosphere is intense but remains open for the viewer to hang their own story on the picture."
Image copyrightSIMON ANNAND
Cate Blanchett at the Albery Theatre for Plenty by David Hare in 1999
Blanchett played the heroine Susan Traherne in a post-war drama spanning 20 years.
Annand: "The first photograph I ever took of Cate. She entered the dressing room, rolled a cigarette and was contemplating the performance ahead. Taken through the mirror.
"This is not a pose, as some have asked, but the coming together of her demands during the day, going on the stage in 40 minutes and the presence of a photographer in the dressing room.
"I have always chosen Cate as my favourite person to photograph, especially as she chose not to chuck me out at a time when privacy might have preferable. Her openness and willingness not to shut down is, in my view, one of her greatest strengths as an artist."
Image copyrightSIMON ANNAND
Jude Law for Hamlet at Wyndham's Theatre in 2009
Law played the tragic Danish prince in a modern-day staging of the Shakespeare classic.
Annand: "Jude was a very popular leader of the company. The image of Fred Astaire was an antidote to the difficulties of playing the troubled Dane.
"It is often remarked by actors that the more intense a story is, and Hamlet is one of the most complex, the more it is necessary to create a mood of light relief backstage. The atmosphere that evening was very playful and this photo shows the actor beginning to take on the demands of a role, minutes before leaving the room."
Phoebe Waller Bridge for Rope by Patrick Hamilton at the Almeida in 2010
Waller-Bridge played Leila Arden in a murder thriller set amidst the privilege and emptiness of the jazz age.
Annand: "The first time I had the good fortune to photograph Phoebe was two or three years before this at The Bush.
"The sense of her unabashed brightness was noticeable and very refreshing. It's no accident she is adored by the many who know her work."
Dame Judi Dench for Peter and Alice by John Logan at the Noel Coward Theatre in 2013
Dame Judi starred alongside Ben Whishaw in a story of loss and grief.
Annand: "This is an image of the great actress just after a conversation about her late and beloved husband Michael Williams.
"Judi has always been a supporter of The Half, for which I am forever grateful. It is a privilege to witness her in a moment of introspection and it seemed like her arm was extended to embrace a cherished absence."
Tom Hardy for Festen by David Eldridge at the Almeida in 2004
Hardy played Michael in the production based on the first of the Dogme films and which tackles the long-term consequences of child abuse.
Annand: "He is reading the script of a Mission Impossible film… People are sometimes surprised at how Tom looked then.
"He appeared supremely confident and in a way plotting the future which was to be so successful. The kind of presence you cannot miss in a room."
Sheila Atim for The Girl of the North Country by Conor McPherson at the Noel Coward theatre in 2018
Atim played Marianne Laine in the musical based on the work of Bob Dylan and set during the winter of the Great Depression in the US.
Annand: "Sheila is about to become world famous in the prequel to Game of Thrones.
"Everyone in the business has followed her steady rise to stardom over the last four or five years. She has a voice like an angel, is a delight to work with and deserves every credit she will undoubtedly receive."
Stephen Fry for Twelfth Night at The Globe in 2012
Fry played the killjoy Malvolio in the Shakespeare comedy.
Annand: "Stephen's performance as Malvolio was his first in a theatre since prematurely leaving a West End production of Cellmates in 1995 after an attack of stage fright.
"It seemed charming and wonderfully brave to have chosen the unpopular malcontent for his comeback. Another triumph in a long line of English archetypes he has crafted for his fortunate audience."
Colin Firth for The Lonely Road by Christopher Fetts at the Old Vic in 1985
Firth played Felix in a story of family deception set in Vienna at the beginning of the 20th Century.
Annand: "Colin Firth playing in the theatre before his film/TV career took off.
"There are some performers who, when they first appear on the scene, it is self-evident very early on they are born to channel certain aspects of human nature. Colin Firth is one of them. It is the theatre's loss that this wonderful actor has not appeared more often on the stage."
Anthony Hopkins at the National Theatre in 1986 for Pravda by David Hare and Howard Brenton
Hopkins played the Murdoch-like media tycoon Lambert Le Roux in the satirical comedy about Fleet Street.
Annand: "Just back from a long time away in America, preparing for his extraordinary performance in Pravda at the NT. Like many great film stars, to whom the camera is attracted, his head seems large in proportion to his shoulders.
"He initially reneged on an agreement to be seen. After reminding him of his senior position in the business, and my intention to promote theatre as live performance, he liked my determination not to give up and enthusiastically gave me two hours for the session.
"In those days the session was accompanied by an interview and a tiny recorder can be seen on the left [of the bottom right-hand photo]."
Meera Syal for Annie at the Piccadilly Theatre in 2017
Syal played the formidable children's home mistress Miss Hannigan in the classic musical.
Annand: "It has always fascinated me why an actor chooses a certain role, and then to see the manifestation he or she will give to the character, especially if a heightened style is used.
"The make-up for Meera as Miss Hannigan, the cruel alcoholic who hates children, is a perfect combination to convey the awfulness of the character but it also adds a certain vibrant attraction. Satan was after all an angel who was thrown out of heaven and then tried to take all the other angels with him, down to hell."
David Tennant for The Rivals by Richard Brinsley Sheridan at the RSC in 2001
Tennant played Jack Absolute in this classic comedy of errors from 1775 set in five acts and telling the story of the romantic difficulties of Lydia Languish.
Annand: "[Theatre director] Marianne Elliot's mother, Rosalind Knight [actress], said there is a wonderful new talent down at the RSC. Knowing Rosalind had the authority to make trustworthy recommendations, considerable effort was made to secure a session with him. The camera loves a quick and quirky intelligence."
The Half opens on 7 September at the Lawrence Batley Theatre in Huddersfield and runs until February.