yes dont fert now those plants dont need anything. when plants need something you will notice it going yellow-ish or brown spots then you can be sure and start ferting first half of the real thing then gradually move up and full. yea you can see sex before flowering. dont flower too early keep us posted with pics and we can help out telling you when should be fine .

i use cfls on my grow and dont matter when you flower plant grows a little then not much after that. with hps they double / triple size ive heard and seen from pics of other users. i would always veg to the maximum limit i have no troubles waiting and think of it its just another 1-2 weeks and you get 20% more of yield.. yummy. how many plants do you have ?