would the plants be a lot bigger by harvest time if i start them inside until a foot tall each compared to if i just plant the seed in a few weeks outside?
Well, obviously yes. If you put them outside after last frost and they are a foot tall you just cut out about 4 weeks right there.

My clones will be ranging from 6 inches to just over a foot by last frost when they go out. My 3 moms, which are going too, will be masive bushes.