There is no simple answer to your question. There are two schools of thought on this particular topic.

1. Bucks are ready to mate pretty much anytime so using estrus shouldn't hurt anything. (I've had deer come up in the beginning of October to estrus both bucks and does first buck I ever shot with a bow caming running straight to the smell after I bleated.)

2. Even though bucks are ready to mate at anytime the smell of estrus in the woods is out of place and could spook the deer. (It could have been another smell that spooked the deer but he was right in the area where the scent would be blowing on him but shouldn't have been in a spot that my human scent would have hit him this has happened twice)

Here is my opinion I've tried both and I've gotten both results. So try it if it works for you then go with it. If it doesn't then don't use it again until the rut is in full swing.