you will start to see the very first pistils during the summer but they will be very few in number. these are called "preflowers." the buds will really start developing 2-3 weeks after the daylight drops below 12 hours.
according to
this chart, daylight in illinois fall below 12 hours in late september. so in late September you should start seeing pistils shoot out everywhere. if you see any plants with ball like structures, they are male and need to be destroyed immediately unless you want to make seeds. the problem with making seeds is that is gives you less bud to smoke.
you may already know this but think of female flowers/buds as a 40 year old cougar looking to make babies before her biological clock expires. if no man will have sex with her(i.e. there is no male pollen around), she dresses sluttier and sluttier hoping one will fuck her(i.e. buds get bigger and bigger hoping to catch some pollen). if you are looking for a large amount of bud, you want the sluttiest female marijuana plant you can get because the buds are huge. if a male comes along and fucks the female by pollinating her, she dresses less slutty(i.e. smaller buds) because she has gotten what she needs to make babies(i.e. seeds). instead of putting all her energy into getting slutty and making big buds, she puts all her energy toward making seeds and puts a hold on making buds leaving you with less marijuana to smoke.
pollinated buds means a lot less marijuana for you to smoke. to solve this problem you kill the males early on so that there is no pollen to limit the bud size.