I can't speak for the modern day Missouri Sportswriters and Sportscasters Association (I do wish I were still a member) ... between 1997-2004 the association met the Sunday morning after the state football championships concluded and selected the all-state teams. Usually was released a week later as long as representatives from each part of the state were present. I seem to recall a year, maybe two were the preps beat guy from Cape Girardeau who had all of the nominees for Southeast Missouri missed the meeting and the chairman made sure to get with him later to make sure that part of the state was included.
Traditionally KC Star had its preps guy (Derek Samson at that time, now managing editor with Rivals.com), same with the St. Louis Post Dispatch, Tom Rackers from Jeff City Tribune was the chairman, Russ "Big Game" Baer from the Columbia Tribune, Joe Kress and Kyle Neddenreip from the Springfield News-Leader, Anvil and I from the Joplin Globe and sometimes Kirksville and Lebanon would have a guy there. I can't recall the prep guy at Cape Girardeau either.
But the goal was usually to have sent out statewide the Tuesday the weekend after the state championships concluded -- in other words today -- in order for it to be printed in the Wednesday morning editions. This could have changed over the years.