Alright for most people your temps seem perfect. To me we don't use the cool down method. We leave our snake room at 82-84 degrees and then the hot spot is left at 90-95 degree. We pair snakes up on Sunday night and then pull the males on Thursday morning. Feed on Saturday and repeat the process. The time it takes a snake to lock up is determined by that snake. All snakes are different. We had males jump right into breeding and some take almost all season before we see a lock. Another factor can be if it is their first season. Sometimes a female wont produce if it is her first season. keep pairing them up week after week and be patient. Oh another thing is you do know that if you produce a desert female that female will not be able to produce viable eggs in the future.