Welcome to the forum. Starting around week 5 it takes 2-3 weeks for all the male flowers to open and drop their pollen. I would suggest you collect the pollen and do a controlled pollination of several branches. If you just let them go on their own you may get up to 2,000 seeds per plant. Seed viability starts to drop after a couple of years, so unless you're planting hundreds at a time many of those seeds will go bad before you'll be able to grow them.