One of the productivity principles I live by is to front load my week. That means I try to book as much as possible into the early part of my week so I'm not crammed late in the week.
My goal is to be done with my message by Wednesday afternoon. That gives me time to think it over and make the appropriate changes on Thursday and Friday.
If I started working on the my message on Thursday, there's very little time to make course corrections.
That's why I like getting my meetings out of the way on Monday so I can focus on other things for the rest of the week. Plus, if you wait until Thursday to have your meetings, any decisions you make won't get started on until next week.