Doesn't need pruning.

Agree, don't do it. Oaks make a wonderful shape without any help from us.

It shouldn't as said already...

I would only remove crossing branches, and lightly head back branches on the intended trunk, to keep them small for later removal. The best time for pruning is in mid summer, to avoid encouraging sucker growth and "brooms". As it matures, it will need little or no pruning.