Foliar feeding with a dilute nutrient solution will speed the delivery of nutrients in particular if you are having a deficiency, I wouldn't do it more then once a month.

I'm curious what the hurry is to bud them? They are so small you'll get a few buds which will be smoked in a week. I would keep the lower vegetation trimmed to the stalk and try to develop just a really nice cola bud if you don't want to grow them out. In that container I can't imagine it will grow much more then 3-4 ft, you can bend them 6-12" from the top if they start getting too tall.

My experience with clones is they grow MUCH slower the first 60 days then fresh seeds.