Never too late and you are doing them a favor by telling them not to waste anymore time on your application because you will be going somewhere else.
I had one for UNLV this Thursday but I got into Marquette so I withdrew this morning... no big deal...
Unfortunately I had to cancel my Nova interview for TOMORROW! I had my tickets and hotel paid for and everything, but personal issues came up 
. I feel terrible about it. And I couldnt even get through so I had to send an email. Ugh.
. I feel terrible about it. And I couldnt even get through so I had to send an email. Ugh.i just cancelled 2 interviews that were scheduled for next week. i think they appreciate you not wasting their time if you aren't considering their school. tufts promptly emailed me back thanking me for the notice and wishing me the best of luck making my decision.