Welcome to the hobby rjm, you are in for a real treat...
I have a few comments about the Nexstar, but please take them with a grain of salt as you may have already done this. Over the last year or so I have had the opportunity to prepare 5 different Nexstar's for flight and have flown 4 of them. It is a good model and after a little tweaking and getting used to, it flies very well. However, there are a few things I have noticed on almost every one of them. At least one of the servos, (either elevator or rudder), is almost always loose. Make sure you check all the servos that they are snug and don't flop around in the servo tray. 3 of the planes I dealt with had this problem.

Check the tightness of the prop nut and spinner. This seems to be a concern as well. A few of the planes I dealt with also had a problem with the landing gear locking into place which caused one of them to land with only one main wheel and the other one somewhere else.

The engine is supposed to have been broken in at the factory, but it may help to keep it a little rich for the first few flights, just to be sure. I am at a higher elevation than most so all the the engines I have had anything to do with needed a fair amount of adjustment, but I don't know if that is the case in other places.

Suffice to say, give the plane a good check and make sure that everything is tight, the batteries are charged, and just have fun.

Hope this helps,

T.