My females will start refusing food and the males when they know they are good to go and about to ovulate and the males seem to know and dont try, so I stop pairing at this point. As far as locking after ovulation, theres no point, shes already gravid. Snakes lay inverted for all sorts of reasons, she could be building, ect. I have juveniles/sub adults that will lay somewhat on their sides after a big meal and so on. The only time I see my breeding females laying inverted or contorted is a couple weeks before they are going to lay and at this point it is obvious they are full of eggs that they are trying to position.