I usually take about 4-5 weeks, in 3-4 stages, I'll harvest the cola and as many other buds around the top as seem ready.
After a week or two, the next set of buds will have grown a bit and matured, time for a second harvest. Same with the rest of buds. This way ya don't end up with so many tiny popcorn buds that are so annoying to trim:>)