How long do I have to play Grand Theft Auto V to unlock all of San Andreas?

I just got an e-mail saying that my GTAV has arrived at my house (I'm in New Zealand, so it's Tuesday morning).

So in anticipation of happily wasting hundreds of hours of my life I'm going to pre-emptively ask this question.

Every other GTA game has locked out sections of the game map until you advance to a certain part of the story. There are also generally tutorial style missions that need to be completed.

I just want to be able to get out and explore all of San Andreas (preferably by dirt bike and mountain bike) so can someone who's faster than me let me know how much gameplay is required to gain access to the entire game map?

Okay, the good news is it seems that you get full access after the second mission (Franklin and Lamar) - which was under 30 minutes of gameplay for me.

After the mission I stole the nearest car and circumnavigated the game map. I didn't come across any barriers at all. Or ate least barriers I could find.

Here's the kicker - it took me 40 minutes to circumnavigate the map by car - that did include a couple of dead-ends, off-road excursions in a hybrid, and a head-on with a train. But still - this is one big playground for us. Cheers Rockstar!