To the OP, try to enjoy the nice break before IFS/UPT/career flying. Go on a cruise, sit on a beach, go fly some acro, spend more than a few days with family. If you can't stop yourself from doing something to prepare, here's a few options. You can find anything with an AFI or AFM at the beginning at www.e-publishing.af.mil with the search bar on the right side.
1. Boldface/ops limits - as stated, start working on them about a month before, to the point where you can write and say them perfectly and without hesitation.
2. AFI 11-202V3 - Browse, but don't study too deeply. The things in there that will be important later involve when you can or cannot fly due to you, your situation, or the weather.
3. AFMAN 11-217V1 - Again, browse, but don't study. Look for bold italicized stuff.
4. Do some fun flying at your local airport in a variety of planes and gliders. Get exposed to different systems, avionics, and techniques. Don't do it to build hours or qualify for something specific. Do it to make yourself a better and more adaptable aviator. If you're not having fun, you're doing something wrong.
Don't forget that all of these things are a secondary priority to taking care of your family and yourself. You're about to start an interesting journey where your own priorities will often be secondary to the needs of the nation, the Air Force, and your many bosses.
Good luck