It's always best to shoot from the same shoulder as your dominant eye, to keep your head upright. Youngters usually have no problem swapping, if you're set in your ways, it will feel wrong at first.
The worst case I saw was my Dad, who was right eyed, left handed, and used a RH 12 bore. The cast in the stock threw the barrels even further out to the left, so his head was in a really weird position.!

Gus