@Brittani7
no, it is not rude, the private host is not a hotel with 24/7 staff and the reception. We have our lives, errands, jobs, etc... and we have to plan our day.
We always ask for the EXACT time of arrival and if we don't get it until the day of check-in then we send them a message:
"Dear xx it seems we still don't have your exact time of arrival, but no problem, you can call us when you arrive at the location and we will do our best to come and meet you within an hour. While waiting you may sit in a nearby cafe. "
It works every time, they answer immediately 🙂