help! me with this harvesting problem please!

hi. i have 2 plants in my small closet grow.they are almost 6 weeks into flower. i have read somewere that if the bottom buds are not fully grown by the time the top half of the plant is ready due to insufficient light getting to them, then it is possible to harvest the top half and then leave the bottom half to grow for a week or so more, allowing the light that the top half was blocking to get to them! is this a valid option? if so can you tell me how i would go about doing this?? or reffer me to a internet page that would tell me?? also one more quick question if you dont mind. when you go to harvest the plants, i know that you cut the branches off at the stem to hang them, but what do i do with the main cola( main stem) where do i cut that?? becoz most of my buds are tightly bunched together on the main stem. that i would say is about a big as a average mans for arm! thanks alot for any good info, its getting close to the harvesting bit for me now and all my hard work is guna pay off!!! so i wana make sure i do the last bit right so as not to ruin evrything!

there is a whole section on Harvesting and Curing.