wow nice stuff man! I got a scope at radioshack for about 10 bucks but without it your best sign of when to harves is to like you said watch the plant... close to harves parts of the plant will begin to die.. like the bottom first set of leaves, and you will see the pistils of the buds die, and draw back into the flower. once it does this it will prob be best to harves I would switch to plain water at like 7 to 8 weeks and then choose when to harvest after atleast 2 weeks of plain water... my own oppinion, but the scope does help and a good one at radioshack is actually really cheap... remember you dont have to harvest all at once...