I'll wait until the first time I can free roam as Trevor, check out his home, then drive around some of the little towns in the countryside in his car. Like some other people said, I like to roleplay at the start of GTA games. So only take things when they're given to me like guns and cars. I'll visit Ammunaton too just to browse what's there.
Although if it gets confirmed that you can rob stores at gunpoint I may try to get a pistol or wait until I am given one and hold up some shops.
Always have something to look forward to. What I'm looking forward to: GTAV