I think they started in 2008/2009. They probably had one team working on the DLC for IV, one helping other studios with Red Dead Redemption/Max Payne 3 and one working exclusively on V.
With majority of the work done on Max Payne 3, which was then due to release in March
2012, they announced GTA V in October (5 months before MP3 release) and that it was in "full development" which I think here means "We're now working full time on GTA V since we have no other games to release." Obviously, Max Payne was delayed by 2 months. I think if they knew Max Payne 3 was gonna be out in May then they would have waited to about January to announce GTA V instead of in October. That would mean we'd only have a 6 month wait between the trailer/screenshots and it wouldn't have been such a pain in the ass for us fans to wait.
In the last 11 months they have been working real hard to get it finished. When the trailer was released they had obviously got most of the map complete (some of it looks unfinished) and I'm sure the story was finished being written. I think that the game must be almost complete by now and that all they have to do is polish things up, make sure everything is working and pick out as many bugs/glitches as possible. In January this year Rockstar North advertised for game testers. Say it took them a month to get everyone started working on the game then it means they have done ~8 months worth of testing. Not sure if it's a long time or not for that sort of thing.
I really think the game will be out March-May 2013. Retailers need 4-6 month notice before a game goes on sale so they can sort pre orders/bundles/deals etc out. Also, no matter what people say, Rockstar need to market the game. I think we'll definitely hear something in the next month or two which is October/November (when the game was announced/trailer released).
I'm thinking October is most likely since Rockstar said on the 24th August "a few weeks or so". It's been almost 5 weeks now since they said that and 5 weeks is definitely pushing the definition of "few" but they said "or so" which gives them some extra time of about 2 weeks AT THE MOST! I expect we'll get something around 15th/22nd October which will be almost a year since the announcement.
Edited by JaggySnake, 27 September 2012 - 12:11 PM.