You really shouldn't wax a brand new car for at least 6 months (better if a year) from when it is built. Reason being is that the paint/clearcoat is still drying up in that time. Waxing during this critical time will cause the clearcoat to bubble up prematurely and fall off. At least this is the theory I heard anyways.
I usually though don't wax the car, I just use Meguiar's quick detailing spray after a nice hand car wash. Lasts for a few and won't drain you as much as the elbow grease required for a good wax job. (plus you can take it with you when moments require the extra bling factor)