It's fine (and just plain sensible to switch it on) .... often there is a limited period "lemon" clause which guarantees a new machine rather than repairing yours (in addition to the normal warranty) if it's DOA (dead on arrival)
HOWEVER
when you switch on the machine you well be forced into a mini-setup to enter serial numbers, create user IDs passwords and activate the software etc.
If the boy is indeed a boy .... you should probably have access to his machine (just in case!!) - so go ahead!
if he's the older variety ... he'll want his privacy ....
mmmmm sounds like a rock and a hard place ;-)
you can send a card with your own machine (how else could you be talking to us?) - but beware many of the "free card sites are "Free" because they spread vuruses, spyware etc (nothing is ever free!!! in internetland)