I have found that keeping the hot spot the same and lowering the cool side temp seems to work better for me. It lets me better tell with a female is cool seeking and when they are heat seeking.

As for when I start pairing animals I started really early last year like October. But normally I try to start in November. There are females that I wont start breeding till Jan or march simply because they weren't up to weight or in past years they have been late to lay anyway so why waste the male on months of pairing just to have them lay in Aug again just like they did for the last 4 years..