Hi JustLegalizeIt
With three Killa-Watt plants it is best to veg them for about three weeks, top them and veg them another twoo-three weeks.
Train the branches so they all get similar amounts of light, air etc., and try to keep the MH light as close to the plants as possible to prevent stretching.
you could easily get a few ounces per plant this way, even more if the plants grow healthy and bushy, but hard to promise yields.
If you can utilize all the light/lumes and provide enough air/co2 than you should be able to harvest up to 250-ish grams, 1 gr/watt.
Good luck, i will follow your grow and help out whenever i can.
Peace
Amsterdammer