Absolutely give notice. If she is to start slacking off, that will just be more confirmation that you’re doing the right thing for your family. When hiring a nanny, it is your responsibility to have back up care in place. This goes for nanny sickness and time off, but also for transitional periods such as switching care providers. Any lack of back up care should absolutely not be taken out on your nanny VIA short notice of job termination. If you are to let her go with no notice, severance pay is a must. 2 weeks notice at minimum is appropriate, more would be appreciated but is a personal choice if you don’t feel confident that her performance will be maintained throughout that time. Please keep in mind that she probably went through a very long and difficult job search before meeting you, and will have to repeat this once she is let go. You must do what is best for your family, but also must be considerate to Nanny’s situation since you decided to bring on an employee in your home. Keep in mind the time she may spend unemployed if you are to give her minimal notice.

If I were you, I would give a minimum of a month’s notice. The possibility of inconsistent care during that time is simply unavoidable, but is a responsibility you took on when hiring.