He's a legendary qb, he passed elite a long, long time ago. I'd say by year 2.
His resume speaks for itself. The guy has been great on the stat sheet, but actually watching and marveling at the way he's played football is another thing IMO. There have been many of them, but the pass to Hines against Jacksonville in (I think) 2005 where he was draped with defenders and still threw a strike ranks up there on the all-time "wow" plays. Even Jack Del Rio was stunned when he was asked about the play. There are so many others, it's actually hard to count them.
He's an all-time great football player and I feel lucky to have watched him from his first snap against Baltimore to the current day.