harvesting one plant at two different times?

i have heard that if you have a plant where the the top buds are maturing faster than the bottom buds, then it is possible to pick the mature buds first and then continue to grow the bottom of the plant until those buds become mature enough for havest.

is this truely possible?

and if it is, then exactly how do i go about doing it? Should i pick the mature buds off individually or should i just cut the top stalk off (the one that has all the mature buds on it) and dry it out?

Yes you can do that.
All depends on where the buds mature..If its the main cola, just chop it at the main stem and leave the others to mature to their fullest..Sometimes the lower buds will ripen first, same goes, pick those(use a sterile scalpel) and leave the main cola to continue until its ready