Congrats and welcome.
You're gonna get a lot of info on this site so take your time to sift through it.
@mark_m is right on everything he listed, get the boat and safety sorted out first, you got time to get used to the boat.
My humble suggestions aside from what mark stated.
1) Go over the boat and learn it inside and out while in your driveway. You can go over how it handles, docking, launching... etc later.
2) practice trailering, she's a 21 ft and she's got a bit of ass to her (not phat like the 24 footers) but some good size ass that you'll need to get used to trailering and turning.
3) Practice backing her up in a very large paring lot. use the paring spots as the "ramp" and do it over an over and over and over until you're comfortable. I did this with my wife and she can "back that thing up like a champ"now. lol
4) USE A CHECKLIST!!!!! Every good boater should utilize a checklist. it ensures you've covered anything pertaining to your boat and fun for the day. Those who don't, eventually will forget the plug... guaranteed. then you're up shit creek.
5) Use the people on here as an encyclopedia. Everyone here is ready to help with any questions (no matter how small) so you enjoy your boat.
6) At minimum, watch a safety video to familiarize yourself with nautical terms, laws and how not to be "that guy" on the water. One of the guys on here put a quick little vid together (Rob's DIY Yamaha) that is a good little snapshot on etiquette... There will be a test at the end...