1 time growing

this is my first time growing and im using 600 watt metal halide for veg phase and a 600 watt hps for the flowering phase. My plants have been in veg for 4 month and they consist of 6 durbans and 3 white widows. the durbans are 36 inches tall and the widows are 20 inches and very bushy. how tall should i expect them to get when i switch them to the flowering phase? any idea on how much i should yeild. Also having a problem getting my clones to take any tips?

Veg for 4 months? That's plenty. I vegged for 4 weeks. The height they will achieve when you flower them is mostly dictated by the genetics. They will jump to their desired height in the first 3 weeks of flowering. Mine went from 24" tall to about 55" in the last 2 weeks.