The PTS P-51 is an EXCELLENT first plane/trainer.

I soloed with mine on the first day out and certified on my third day out.

The included sim is junk.

I spent a good five months practicing on G3 before my first time at the field. Needless to say this helped a lot. Spend the money on a good sim, it will pay off many times over.

It is advisable (if you haven't already done so) to join a local club and of course get your memberships in order.

Most clubs provide training and certification.

Don't think about this, DO IT!

You'll be able to keep you nice new plane intact this way.

Head over to the LONG PTS thread on the ARF forums. There are several things you need to do to it before your first flight.
Note that you'll also see many things there that are not urgent, but are optional.

If it is available see if the club has a trainer and take that up with the instructor for the first flight or two, to get orientation, etc down.

Don't be in a hurry to fly your PTS, do it only when you are ready for it.