you have until the pollen sacks open. which is usually 5-6 weeks into flowering. before that, there is no released pollen to fertilize the girls. however, if u wait too long and chop it down, the plant will panic, and if the sacs are large enough they will open up after its chopped down, and release pollen. so basiccally, u have alot more time, but after u cut it, put it in a plastic bag and throw it out to be sure the buds on ur girls dont become pollenated.
but no, the pollen sacs have to be at least the size of a pea to have any trace amounts of pollen.
btw, if u plan on making seeds and breeding, just a heads up, the pollen will make u have allergies like crazy.