Short answer. They go when they are ready and if they feel like it. Ive had girls ovulate after pairing for 3-4 months and some that went after pairing for 7. Then on top of that another month and a half to 2 months before laying. Patience is key. Look for the signs of building and building behavior once you get them down youll know when shes getting close to going for you. Then once you catch an ovulation you can start the countdown. Unless she changes her mind that is. Good luck