You are entitled to holidays and you need holidays to refresh and recharge. It is not your problem if the parents don't have backup care. Most parents book their holidays when the provider has hers.... If they choose not to do that... Not your problem! You should give at least a months notice for your time off. Most companies require you to submit your request for holiday time in February, so that us when I choose mine and inform my families. Plan your holidays and put a notice on your door informing the parents Monday morning when they arrive, and point it out to them.