I dive at least two or three times a week (when I can get my tanks filled.) Been diving since the early 90's. I think I'd go stir crazy if I couldn't dive.
If you have your own equipment check it out, see how to put it together, get used it. Of course when in doubt leave it alone. Don't go tearing apart your first or second stage. Most long time divers I know have never torn down a first stage. But check out how the BC, Gauges and Regulators are assembled. Adjust the BC so it fits you correctly.
If you have your books already you can start learning your dive tables. Knowing how they work and what they mean ahead of time makes quick work of a rather boring, yet important, part of the course. Not getting "bent" is right up there with not drowning when it comes to having a successful dive.
Here's a link to a site that helps (not my favorite) but it's free and free is a very good price-
Link Here
I'll also second the above comment to work on buoyancy. I have somewhere around 1000 dives. I see divers all the time that say they have 100's of dive yet they jump in the water and can not maintain a depth. I almost always take extra weight with me because I end up with people who overfill their BC's and can't stay down. It's easier to pass off a couple leads then train someone you don't know underwater. I've always gone by the rule that if you jump in the water and exhale you should sink to you mouth, when you inhale you're shoulders should be about surface level. Your lungs are basically built in BC's. Practice breathing in and out and see how much you ascend and descend. And yes you should be able to maintain yourself about 6" off the bottom, belly down, for an extended period of time without effort or movement. If you can do that you're head of a lot of long time divers I know.
Don't work to hard at anything underwater, let everyone else run out of their air swimming around in circles. Relax enjoy yourself and have fun.