So, here I am in week four of bloom, when I spotted pollen sacks on some of my buds. Upon further inspection, I found one that had already fully opened. What do I do now?
Sit back and wait to be a father More than likely it already has done its job of pollinating your other plants. You can pull that plant and watch the other ones closely. I would start flushing the plants now so you could at least have some smoke.