I'm not sure what time RIAT opens or when the flying starts (usually 11?) - expect to queue at any time, but once the gates open it moves swiftly enough.
RIAT is big. The concept of getting a good look around before the crowds flood in doesn't really apply in the same way it does elsewhere. There is plenty of room on the site, but for photography, the ropes are often too close to the aircraft for you to get clear shots of many of the airframes without someone or something getting in the way, but the plus side is that you can get close. There are less people around very early and very late, obviously, but even when you get in early, you don't have long before the place seems busy. You won't get a good look at everything in the static and be able to concentrate on all the aerial displays, I usually miss the first few displays as I'm still walking around the static. It's difficult to do justice to the whole event in a single day.
I wouldn't worry about it too much. Just turn up, with plenty of food, water, a hat, suncream and a mac for the rain and see what happens. After a few visits, you'll find your own preferred way of enjoying the show.
Erm, is this thing on?