I forgot to mention the side that opposes the bell shaped curve idea, this other side of the deer biology house believes that estrous cycles are skewed towards the right, meaning:
The smallest percentage of does come into estrous early
The largest percentage of does come into estrous during November
The leftovers who either:
A. haven't come into estrous yet, or
B. were not bred during their first peak estrous, will come back into heat during December and possibly even into January.
This model seems more realistic to me.