I used to do the standard 2 weeks, but I have switched to 4 weeks notice. This way, their 2 week deposit covers their LAST 2 weeks, provided they give the 4 weeks notice and pay for the first 2 weeks of it.

I hated the way it was before, where parents could just show up on payday and give their notice rather than any money on that day. No time to juggle the budget if necessary. I like a bit more time to plan and prepare.