For many years I did not brumate my breeding corns. Then I started to put them down right before Thanksgiving and bring them but up in early February; so essentially 3 months of dark and temps hovering around 54F. The difference I found was the ease and consistency of breeding. Without brumation breeding was hit or miss. With brumation the entire colony cycled at the same time so I was able to pair up, collect egg, incubate and hatch within a 90ish day window. It was easier to know when the females would be receptive to mating as well. I rarely missed an ovulation in this manner so I continue to brumate the breeders to this day.
As to how long they have to be brumated for this to work I've never truly tested. I've heard people in warmer climates might only get a 30 day window where it is cool enough to achieve brumation temps without artificial cooling. But brumation is more than just temperature driven. Day light duration, food availability AND temperature drive the need to brumate in the wild. There is no harm in trying to breed with a limited down time; I've succeeded with none.
PS-Males will breed a stick or your arm when you pick the up to put them with the intended female! So don't base your timing on their readiness to breed. lol
