Even on Wednesday and even when the public isn't let in yet, rush to get an 18+ band, then rush the things you want to see first. The queues build up ridiculuously fast, especially for anything 18+, which is hosted in stupid small cabins, so that even when only press are inside, there can be queues of 30 minutes or longer easily.
Not on the press day, my best experience was to not get an 18+ band first, then rush inside and get an 18+ there, and then queue up for what you want to see (for me it was the Vita - we were just in time before a large queue built up there, and any of the larger games are much worse than that).
All the non 18+ stuff is much easier to see and get to, so make that a lower priority. I was lucky enough to like that, but I'm still not planning to go back until the cabins have been abandoned, and you can just walk around watching other people play no matter the game's age rating. I still had a lot of fun though when I was there, trying Move games and such and talking to the Move Fitness developer