it'll produce pollen sacs from about 10 days after it shows until it's all yellow, shriveled and dead. will live quite some time too to be honest.
now for seed development you need a good 6 weeks. i typially polinate the 3rd through the 5th week of flowering and then stop it from getting more pollen. mainly because it takes time for seeds to develop and if it continues to get pollen there will be tons of worthless seeds. then i let it go until the trich are bent over, laying flat, heads broken off half the time, dark brown, way past amber. i continue to feed it nutrients just the same as if it weren't pollinated. then i flush, again just as if it were normal as i will still smoke it or make hash out of it after i harvest my seed stock.