Time Based reminders based on an open field within a lead

Time Based reminders based on an open field within a lead

Hello,
I am trying to figure out how to set up an automatic reminder when I mark a lead a specific criteria.  For example I have a section in my leads where I can rate them A, B, or C. When I mark a lead as A I want to automatically be reminded 1 month from then to send them and email, 2 months from that time to call them and 3 months from that time to send them a physical mail piece.  I have different desires for each A, B and C lead but that is the jist of it.  Does anyone know if this is possible?