Agreed. Veg for at least 6 weeks total. Keep in mind that they will stretch during flowering, possibly doubling in size. But you've done some LST in the early stages which gives them plenty of room to grow.
As for the harvest amount, a lot of factors come into consideration (strain/lineage, nutrients, etc) but if you started flowering in 2 weeks, you'd be lucky to get an ounce off of each of those girls. Let them veg longer and let them get bigger.