Rockstar North president Leslie Benzies told OXM that the studio wants gamers to have the chance to get to know each of the characters individually.
He explained: "We want to give the player the opportunity to get to know the three characters individually, and explore the world as each of them, and it would not have been possible if all three had been available from the start.
And he also said the game will be faster-paced than previous titles in the series.
"Today, we want to surprise people with very intense missions from the start. The pace of the game is much faster than any of its predecessors.
"From the beginning, we want to show off the new game mechanics while creating intense, action-packed gameplay, to capture the player's attention immediately.
"Remember that the three characters in the game are already living in the city of Los Santos and surrounding areas. They are not newcomers like Niko and Tommy Vercetti, or people returning after a long absence like CJ.
"They already have contacts, they are integrated with the world and lead a busy life - these characteristics should give players a sense of immediate and total immersion."
GTA V will be released on Xbox 360 and PS3 on 17 September.