More than 14,500 people have so far applied to take part
Antony Gormley's Fourth Plinth art project is set to begin in London's Trafalgar Square later.
The One and Other project will see a different person standing on the plinth every hour for 24 hours a day over the next 100 days.
Housewife Rachel Wardell, 35, will take her place as the first "living statue" when the event kicks off at 0900 BST.
More than 14,500 people from across Britain have so far applied to take part in the event.
Ms Wardell will be followed at 1000 BST by Jason Clark, a 41-year-old nurse from Brighton.
Other people to take to the plinth on the first day include Jill Gatcum, 51, a consultant from London, Suren Seneviratne, a 22-year-old Sri Lankan student and artist, and Ishvinder Singh Matharu, a 31-year-old optometrist from Chigwell in Essex.
Heather Pringle will be celebrating her 20th birthday on the plinth
The oldest among July's 615 participants is pensioner Gwynneth Pedler, 83, from Oxford, who plans to signal with semaphore flags.
While Heather Pringle, a student from Hexham, will celebrate her 20th birthday on the plinth.
Living statues for following months will be announced later, with 2,400 people taking part up to 14 October.
Participants are chosen at random by a computer and can do anything they want on the plinth as long as it is legal.
Applications will be accepted until 1 September when the last group of people are chosen.