Must i develop my Bishop on my next move?

For WildeyeQ, after 5.0-0 Nb4  6.Nc3 NxB black will have the advantage of having the bishop pair vs white's NB.

Okay yeah that's true. Thanks so much Clavius 

But instead of developing the b-pawn or g-pawn just to activate your Bishop, why can't you just develop the d-pawn or e-pawn? If you develop the b or g-pawn, your just giving space for your Bishop to move and open up, but if you develop the d or e-pawn, then you could do 2 things. First, you can control the center. Second you don't have to move your Bishop because it already is controlling a diagonal after moving the/a center pawn(s), but if you want to, you could just move your bishop to control a longer diagonal. It's a simple as that!