Hey Thorn-
Blueberry fan all the way. In fact I just harvested my grow of Southern Lights- 1 of the branches I crossed with some blueberry pollen I've been saving in the freezer for about 6 months- I haven't checked for seeds yet, but hopefully I got a new cross to try out on my next grow.
As far as your question-
as soon as you identify the male- of course get it away from your females- but those sacs burst pretty quickly and regularly so it won't take long to collect pollen, couple of days at most. The stuff is extremely small and I've found when collecting it I have more plant matter from the sac itself than I do pollen.
Good luck with your toxic waste grow!