Acer Atropurpureum

Hi would like some advice on whether I should prune my Acer Atropurpureum.  It's only about 2 years old and has Y shaped branches however the top of the branches have now curled so they are crossing at the top forming an O shape.   I had read that I shouldn't prune until the plant is older and should leave to form a more natural shape but am worred if I leave it the branches will just cross.  Any advice greatly appreciated.