depends on your typical plant. It's more about your lighting than it is about the # of plants you have. The more lighting you have, the more your plants can produce.
....room conditions, grow technique, and strain....these determine how heavy of a yield a plant will produce.
have had plants that have given me 1/4 pound and plants that only produce like an OZ. this is partially true, your lighting does play a big part as well as how many plants you pack into the room, but I think that strain plays a huge part in this
Your question is like asking when is it going to be legalized nationwide, your guss is probably as good as any. There is no "typical" average yield it depends on many different variables so impossible to say.