Is it ok to call Interviewer day after to simply Thank them?

I had a Interview at Securitas yesterday, To me it went well and the Interviewer said If I get the Job I will get a call by this wednesday, and If I dont I will get a postcard stating I didnt..I know it is professional to send a post card thanking them but IDK if it will reach them in time so my question is..is It appropriate to Call the Interviewer to simply thank them for taking time out of they're busy day to Interview me? or would it come off as desperate? thanks for the answers