dude - 'practicing' and 'playing' are two completely different things. as a coach, i wouldn't - couldn't - justify starting virtually any rookie in the first game of the season on principle alone (try and keep their ego down). throw in that he's got to handle hot routes, adjusting to blitzes or when a defense changes pre-snap...all of these things take a bit of time.
he WILL be starting by the end of the year - i actually have him as one of my offensive rookie of the year candidates...but i just don't see him being a top 2 receiver on that team until at least sometime in october.
side note, though. jacksonville is stupid if they don't get him on the field when they are in the red zone. i'd have him study what he needs to do there more than anything else. line him up outside...if even in a 1 WR formation - the defense really won't be sure what to expect and they'd almost definitly have to slide extra coverage his way.