1st off. i agree with everyone else.. use the MH during it will deff work better.. and then the HPS for flowering.. and like they said to.. throw some "DAYLIGHT" CFL's along the side of the plant too so those parts of the plants will get some light.. and then when you flower.. throw some 2700K CFL's along the side and sitch the MH for HPS.. you'll be happy with the results.
and as far as clones.. once you see little branches coming off.. then your good to go.. my smaller plants are only 3 weeks old and i could take cuttings off of them if i wanted.. you gotta try to cut it off at a 45 degree angle.. and if you can (with a razor blade) make a few SMALL 45 degree slits at the very bottom of the clone.. maybe like 2 on each side.. that will help jumpstart your clone.. and if you have a few bucks.. go to stop and shop/shaws and get some root hormone stuff.. stop and shop and shaws usually have Schultz take root i think its called for like 3 or 4 bucks.. this will increase the chances of you clones growing by ALOT!!and one last thing.. some people try to take cutitng... and just cut off a branch with the fan leaf on it.. thats NOT wat you want.. lol. you want a branch that comes off that has a few leaves on it.. basically.. if its gonna grow a bud on it.. then you can use it... im sure you might already know this.. but just in case.. dont want oyu to waste your time and hurt your plant...
and as far as your white rhino plants.. they look pretty fucking good to me.. seem slike you have no trouble growing your plants man.. lol its kinda hard to tell exactly how long they have left just from a picture... they deff have a little while longer tho if your only on day 37... id say at least 3-5 weeks.. most plants take 9-11 weeks.. try looking at the hairs.. once all the hairs are 3/4 red.. you should cut it down.. this is kinda wierd.. but you can almost tell when they are done.. because they just "look" done.. do you have a microscope?? if you have one.. just look at the trichs around week 8/9.. ill give you a link... because depending on what type of high you want will depend on when you want to harvest.. i found a chart for you to go by... and if you dont have a scope.. go to radio shack.. you can buy a cheap one their for under $10.. which is really good.. and is the best way to tell if theyre ready or not..
i have a question for you... how long did you veg those white rhino plants for?? because those are like the perfect height for me.. i want my plants to be that size.. lol. and ok.. heres the link...
http://www.stonerforums.com/lounge/attachments/harvesting-drying-curing/889d1180419033-harvesting-trichome-color-2940when-harvest.jpg