light cylces

hey so i've been growing some seedlings for just over a week now. Two of my plants seem to be striving extremely well while the other two are a little less lively. i have my floro's on 24 hrs a day right now. my question is what woul dbe the optimal time cycle for the best and quickest veg? i haven't really found the answer. i don't plan on having them grow past 2 1/2 feet most likely so i want to get there ASAP. and can i switch cycles after the 24 hrs has been in stated.

most growers use 18/6 light cycle for vegetative stage. I like to use 16/8 to save on my electric bill but 18/6 is optimum. If you want your plants to be 2 1/2 feet by harvest time you should induce 12/12 when they are about 13-14 inches tall. Your plant will most likely double in size the first month of flowering.

is it bad to do the 24 hrs.? like why is 18/6 more optimal? and since they have been in a 24 cycle right now is it bad to switch them to 18/6 now?

I have used 24/0, 20/4 and 18/6 and cannot see a differance to the grow, only the electric bill.

Whatever suits you best.

but can i switch mid cycle? will it stress the plants out too much?