Besides he bespoke, that it's even possible to meet other characters in the game if one knows the current location of another. Thus it might be possible to hustle things on by becoming friends as soon as possible. Generally, Rockstar Games broke the mould regarding characters in GTA V - they are much better integrated into society compared to previous main characters and they have direct contacts, which makes it easier to get used to the game world.
GTA V is going to get released on September 17 for Xbox 360 and PlayStation 3. However, there is no information about the release date of the not yet confirmed PC edition.