Do I have to host a minimum number of sessions?
Edited
No. Host as often or as rarely as you like. There's no minimum and no schedule you have to keep. If you decide hosting is not for you, that's okay too.
Two things do matter:
If you schedule a session, show up. Attendees plan their day around it. If you can't make it, cancel ahead of time so another host can pick it up. See How do I cancel a session I'm hosting?
If you want the host incentive, you need to host 10 or more public sessions in a calendar month. See How the host incentive works.
Some hosts find that hosting at a regular time each week can be a way to build habits, but it's all up to you.