I'm so happy you found these two girls! One for each of you to have in your lap, how perfect. Ousier is no doubt smiling! You'll go by your vet's advice, of course, but you asked for personal experience, and we've had our girls spayed at 7-8 months. If it were us, I think we'd do them both at once so I only had to chew my fingernails and watch the clock one day. Then too, as you point out, the boo boo sister won't have the other one trying to get her to play. Don't be afraid of giving them pain meds, if the vet suggests it. Years ago, some vets tended not to prescribe them after surgery, for fear the pet would be too active and disturb the surgery site. That philosophy has changed at many vet practices. Be brave, plan a shopping trip or even go see a movie while they are having surgery, leaving your cell #, of course. Congrats again and let us know when it's all done.