We have been providing our butler a list on every cruise. It indicates what night(s) we are specialty dining (reservations are made prior to boarding), what night we will be dining in our suite (we want to provide a few days notice so that our butler can plan accordingly (we do not request having our meal served course by course, booked shore excursions, etc. Anything that will make it easier for him/her!
I print out a copy of the communication between Shoreside and I and leave it on the dining table.
I certainly do not find this to be rude at all. If it helps the staff to better know know schedules so be it. It has always worked out well for us and hopefully the crew as well.