Mo. Rev. Stat. § 492.200: When notice shall be served.

In all cases where notice is required by sections 492.080 to 492.400, the same shall be served at least three days before the day of taking the depositions, and one day additional for every fifty miles for the first three hundred miles, and beyond that one additional day for each one hundred miles of distance from the place of serving or setting up such notice, to the place of taking the depositions, except as otherwise provided in said sections; provided, that not more than one notice to take depositions in the same case shall be given for the same day.