When do i transplant?

Hello everybody and thank all of you who have posted great information on this site! I am new to growing and have a couple questions if anybody can help me out it would be greatly appreciated......... I have 2 fem wonder woman plants growing (from seed) in 2 seperate 1 gallon black plant buckets. I am using canna coco medium and canna nuts....... They were planted on 8/15 and sprouted on 8/16 I have had them under a 400w hps the whole time......They are now about +/- 6 in tall and starting their 5th node......I have done quite a bit of reading and trying to learn....I now understand what they say about each seed being different and even though it is 1 strain each plant is its own plant!! Wonder woman is a hybrid........One of the plants internodes is quite a bit larger than the others......its like one is taking the indica traits while the other is taking the sativa traits........Anyways lol back to my questions .........The roots have started showing thru the bottom of the container....I dont want them to get root bound and stunt the growth any.....So when would be a good time to transplant them? I was going to do it one time into a 5 gal bucket. Also I made a nub mistake when they were weeeee babies......I put the same water into a spray bottle that i feed them with (nuts and all).......and sprayed them a few times Well I found out they dont like that at all......Now some of the fan leaves have yellow spots.....( I think it is from me spraying them the nuts buring the leaves) But im not sure! If someone could let me know if that is the reason that would be great!! Also will the leaves ever go back to looking good or if they get nut burnt is it a scare for leaf life lol......Ok thats all for now I will try and post some pics real soon