It doesn't really matter.
It all depends on how you would like to counter it. If you would want to come around to the outside gate, right on right would be best. If you want to hit on the inside, right on left and vice versa. If you want to follow up with a lap sau, once again, it doesn't matter which side you bong sau!
But, as others said, bong sau isn't really supposed to be a movement that you should go to first. It should only made when pressure is put on the outside of an extended hand which then collapses into bong sau. "Elbow like iron, Arm like a blade of grass."
The important things are to keep proper structure, constant attack on the centerline, and to NOT chase the hand.
Last edited by BlackEChan; 04-01-2013 at 05:15 PM.
"He who say's does not know, he who knows does not say"
"True Gong Fu is practicing in the coldest days of winter and the dog days of summer"
"Don't try, do"