topping

my plants have only been in 12-12 for one day,do u guys think its a good idea to top them now or is it to late,i have never topped a plant so was just wondering when is a good time to do it,thanks guys for any info

its definatly not too late

Its not "to late" but topping right now will remove the best bud site on your plant and it might not veg much more before budset. Another option is to wait and see where the strongest bud sites develop, then cull some of the weaker flowers. I usually do that cull process to most of my plants in week 2-3 of flowering, letting the plant focus on only the best bud sites.
I always do one last round of pruning about a week before I flip the lights, then they have a few weeks to recover before I cut anything else off them. Remember that cutting stuff off a plant is stressful, so cutting them at a transitional phase may slow then down a bit more.

Never heard of topping at the beginning of flowering, only during veg, lst on the other-hand is all good.

I have had bad lluck doing that. I wouldnt

by the sounds of it,im not gonna do it,ill just throw some screen over them to hold them down a bit,my problem is,i think i veg to long and i dont want to run out of room so to speak,and ideas on how to keep them from stretching to much in flower?there only 2 feet high and my box is only 7ft tall,so do u guys think ill run into a problem,if not ill let them go and see what happends