I would keep up and running while you are trying and once you get pregnant. After you tell dc families you are expecting you don't have to disclose your long term plans until later. Most I would guess would stay until the end of your pregnancy and have something set up for your due date once you tell them your plans. I would leave that till the end (one month notice is plenty or whatever your contract states) where you send them a letter that you will not be offering daycare after new baby arrives. If they ask why you can just say you are only now realizing that it will be too demanding to care for your own 3 children and run a daycare.