Sorry Stinky...I didn't even think to mention taking the lower branches for clones, but he did specifically mention topping.
My bad.
Hudson...you can put the unsexed adult under 12/12 light to determine sex, prior to taking clones. Takes a week or so to start seeing sex, depending on strain and maturity.
Once sex is determined, you can switch back to 18/6, or whatever your veg cycle is. Takes another week or so to revert back to full veg. A total of two or three extra weeks for this process, but you'll know which plant(s) to take clones from, and which are the males.
Do you have seperate veg and flower rooms? Just curious, because you can't veg and flower in the same closet without some serious lightproofing and ventilation handywork.