Well if it was an illness that I knew was going to be the end of her, especially if she was old. I might get another dog in the months before she died. A companion for both of us kind of. The people next door had their dog about fourteen years. Almost the next day after Sadie was put to sleep, they had a new black puppy over there. I'm thinking they researched and planned for that timing.
If it was sudden for Sophie, I'd be starting to look the next week. It'd be too quiet without a dog in the house, even with all the cats, I've gotten used to it.