I am not sure how this is supposed to work. Should your team members check the calendar before they ping you? and if they get annoyed by your lack of responsiveness you point them to the calendar?

Blocking time in your calendar will stop incoming meeting invites, and then at those times my IM status is set to DND.

This idea that people at work should always be available is not a good standard that we've set ourselves up in. If you're in support or some job then yeah, this model won't work for you. If you're coding then it makes a big difference.

You change your status. Others would then know (or should know) your status before reaching out to you.