We appear to meet all 3 early on

[blakeney]

" Though it's not one of the large-scale, full-blown heists that come later in the game, an early mission called Blitz Play was a promising taste of what might come later. Before you can pull off this mission, which owes more than a little to the armored car robbery that takes place early in the film Heat, you need to acquire some vehicles, outfits, masks, and other supplies, and park your getaway car in some isolated spot. The dramatic buildup of this preparation should, in true cinematic style, pay off during the job itself. (After all, the armored car job in Heat wouldn't be quite as exciting without the buildup of seeing De Niro steal the ambulance, Kilmer buy the explosives, and so on.)

 

Once all the preparations have been made, it's go time. As Trevor, you're a lookout, searching for an armored car and letting your cohorts know when it's approaching. As Michael, you park a truck across the road, forcing the armored car to come to a stop. As Franklin, you then speed down an alleyway in a dump truck and run the armored car down, knocking it over. You then plant a bomb on the rear doors of the truck and blow the thing open.

 

It doesn't take long for the cops to show up. Franklin, Trevor, and Michael must work together to get out of there alive, and you can switch between them on the fly to most effectively extricate yourself from the situation. From Trevor's lookout post, for instance, you can fire on the cops with a sniper rifle, offering support to Franklin, who the cops have hemmed in. Your counterparts can fend for themselves when you're not controlling them, but they'll typically leave the really exciting stuff to you. When an opportunity arises to shoot down a police helicopter with a rocket launcher, the game encourages you to switch to that character and do it yourself, rather than letting it happen offscreen."

 

Taken from Gamespot's feature on the "Heist management" side of things