In my opinion the *best* way to get ready for the trail is hands on... this includes your gear. The *best* way to become familiar with your gear is to use it on the field. For example, the more you set up and take down your shelter, the faster you'll get at it, and the more you'll decide whether or not your setup.
For your backpack, since you have some time to prepare, maybe you can find or make some friends who have backpacks they are willing to let you borrow? Even if you can borrow it for just a day, take it and fill it with about 20 pounds of gear (even if you have to use water bottles and pillows), and try to take it on a fairly treacherous hike (lol). This will give you a good idea of how to adjust the straps on backpacks to get a good fit, and decide what you like and don't like about the pack style you're using, etc.
You can do research online and buy a pack you like at the store, and you will probably end up with something good (or great), but it always helps to put a few miles on something and get that first-hand experience. This goes with everything from your shelter and pack to your preferred way of making fire and cooking. --But I know this isn't always easy with expensive gear. Just some advice!