The tour guides that we contacted adjusted the tours to fit our times in port. Just make sure you let them know what cruise and times you will be in port and they will get a schedule to you.
Also, many of the tour guides have the list of which ships are in port on which days, so the good ones likely already know that the Magic isn't getting in until midday on our first day in port. I worked with several tour companies before picking our guide, and they all were able to adjust their tours and schedules to accommodate our ship's docking schedule. Not to worry.