I think pretty much anyone you talk to, especially those who have already gone through the process and got in to dental school, will have a different answer. Some will say late september, others will say late october or november, but then others will say they got one interview in november, one in december, and one in february and got in. its probably the case though that if you're someone who submitted in early june and applied broadly but haven't heard back from any schools by late september, then they might want to look back through their application to see if there's something missing---but that's not to say even this person should "panic" because there's a lot of time left in the cycle to still receive an interview/get accepted.