Wishing you luck in getting some hits for the new year but if not then I would try to give them two months warning but then be willing to let them go with 2 weeks notice whenever they find the care they want. For some it could be right away and some make take longer to interview more people. As well coming up on Christmas it would be nice to tell them but let them know that you will continue for Jan/maybe even into Feb so they can enjoy Christmas and worry about it in the new year. That being said I would continue as long as you want to without saying anything till you have figured out what you want to do instead. That way you will keep the income as long as possible and get to enjoy your Christmas too. Good luck with the decisions.