You should be alright, I normally target to chuck the pollen around week 3 of flowering, that allows a good 4-5 weeks to develop the seeds. I prefer the 5 weeks which is why I pollinate at 3 weeks as most of my strains run 8-9 weeks total in flowering.
Even if the females are at 4 weeks and finish in 8 weeks, you can chop the rest and leave the seeded branches for another week or two to make sure the seeds are mature enough.
When you eventually harvest your seeds, wait about 4 weeks from harvest before popping any, they'll germinate at a much better rate after 4 weeks.