Haha, wow.. this thread is full of a bunch of moronic responses and people living in fear.. trying new things and experimenting is what gardening is all about.. yes, reading and increasing your knowledge base on horticulture will help you be a more successful grower but honestly there are so many variables at play in the real world, you cant expect to read a few threads and think that the values/strategies involved in those grows have any bearing on your own grow.. learning and becoming successful involves trial and error (each crop is different) so play around and try new stuff - thats what I do and Ive come across many things that are just plain myths (like chopping roots - actually people its fine! - just have to know what youre doing).. just like topping late.. its fine! just have to be patient..
THeseaman... dude, youre fine and Im sure your plants are fine and are going to fruit wonderful bud for u to smoke.. I top some strains a whole week or two into flowering and others I dont touch (not even prune) a whole week before flowering.. depends on a host of factors.. your nutrient ratios, lighting (intensity/frequency), strain, etc etc... remember its a WEED.. most people find it actually surprisingly difficult to get rid of weeds from growing in gardens so your plants will be fine, buds grow on all of the branches that get enough light.. so topping like u did after one week into flower and leaving them would have eventually grown a nice pair of buds at the top of the plant with no problems! though each would be slightly smaller than having one main big cola..
it usually takes at least 2 weeks to even see the first hint of regrowth from a topped branch (the main stem takes slightly longer because the plant has to reprogram its growth strategy and so divides the stem into two branches) after a month the main cut stem should have at least an inch or two (usually 4-5 inches) of growth for the two new branches..
SO... here are some suggestions at this point..
prune a few of the lowest/old leaves off of some of the lower branches..
putting them back into veg photoperiod was a mistake but now that they are in veg again, thats fine just make sure they stay veg for another few weeks before putting them (gradually) back into flowering or else there is a chance you may confuse the plant and make it go hermie (bad)..
make sure to give it plenty of nitrogen (phosphates are the best) for regrowth..
and finally be patient.. it takes a while for a plant to recover from such a sudden and violent act of topping (also it kind of does unfortunately cut the most potent part of the plant so yield will be slightly less once u flower - but not much less)..
oh and side note ... just like u said, 24/0 photoperiod in veg is a great thing to do if u dont care about electricity costs.. my plants grow about 5-6 inches daily in 24 hour lighting..
Ive experimented with spraying the top that was cut with 1/4 strength nutrient solution (just a spritz - few droplets onto the top open main stem) each night and it seems to help the healing along (I think that the open stem allows too much outside air and causes a mini air embolism which causes the plant to have to resort to building a resin over the inside tissues near the opening to ward of antigens so this slows tissue regrowth, so constantly closing it with a 1/4 strength solution helps resolve this - I also pinch mine at the top immediately after cutting but dont pinch so hard you hear it crackle)
but dont expect to see any regrowth for at least a couple weeks.. good luck!