We plan on / birthday on Saturday, March 18!

Hello, everybody!
March 20 is 91-year-old birthday of Mr. Mitsumasa Anno.
You follow "# Mitsumasa Anno 91" by all means and post on SNS, and do you not celebrate birthday of teacher together?
We tell Mr. future about message which attaches tag during period of from 18 to 20, and was posted.