Go straight up to your pianist the first time you work with them, introduce yourself saying “Hi, my name is ……”, find out what name your pianist prefers to be called and use it often during class. (Getting the name right is important: not everyone likes ‘maestro’ or ‘our lovely pianist’, ‘the music’ or ‘Mr/s X’ – and they won’t know what to call you unless you tell them.)
Basic social stuff, but it’s a vital part of establishing communication that teachers often neglect through nerves – worried about the class, or afraid of making a mess of their counts and music. A shame really, because once the moment for introductions has passed, it’s difficult to retrieve without some embarrassment and back-pedalling. More to the point, get the pianist on side from the start, and you’ve got a friend and collaborator behind you rather than someone to make you nervous.
Incidentally, I give exactly the same advice to pianists. It doesn’t really matter who makes the first move, as long as you make a social connection before you get down to the business of doing class together.