sup dood, you can veg for as little or as long as you would like, the longer you veg for the greater your yield will be, keep in mind once you start 12/12 your plants will double and maybe even triple in size, its hard to say what your yield is going to be, what strain? what kinda light? I guess your avearage yield would be 2-3 ounces? very hard to say, got any pics of your setup? good luck