You polinate right in that second polen hits flowers..
signs are usually tommorow first hairs going dieing..
if you take water in spray bottle to spray hole plant after polination she will
still be polinated but unwanted polen will not fly away far and deep..
good trick if you wish to smoke other non-polinated plants and you
wish them mostly unseeded..
maybe you get seed here and there but this is minor if you spray water after
polination... ;D