What is classed as the off season, is it the time of year when everyone else has stopped breeding, or is it the time of year when one would expect to gain the least percentage of success. I say that there is no off season, rather there is an all year round season with Ball Pythons.
I had a female wrapping the water bowl in January, I had one wrap in April, and I have one that has started wrapping in the last two weeks.
To date I have only put my first males in with females intentionally last night.
I had a pair unintentionally lock in December and so I put them together intentionally for 4 times through December/January/Febuary, to date the Female is not showing any signs of being gravid.
I have friends who have bred Ball Pythons for years, and they get babies in September, in November, in January.
My personal opinion, Ball Pythons can be paired at any time during the year, if conditions are right, they will lock, and when conditions are right or the Female is ready, she will go through the process and lay eggs etc.
Just my 2 cents worth.