Nobody can tell you this. She might not need to take out probate at all. In fact she may now come into the proceeds of a life insurance policy that would mean she would be able to purchase more quickly. Or she might have to have loan offers reissued based on her sole earnings etc. It really depends on their personal financial circumstances. I'd imagine that the only thing you can do is put a time limit on when contracts must be signed by, despite the fact that I'm sure you want to be respectful of her grief, as you must ensure that you do not lose the house you want to buy etc