How much advanced notice is expected for faculty interviews? I have a faculty interview for a Canadian university coming up some time in the next week. For this interview I have to prepare 2 lectures.

I still havent received the date, nor the lecture topics. So I havent even booked time off work yet. 

How much advanced warning is expected for this sort of thing? I feel that I would need ample time to prepare and with working full time elsewhere, it might be right. Or maybe Im just overreacting and stressing out.
It's totally reasonable for you to want to plan your schedule at least a week ahead.

Contact them and ask if they have the date yet, or if not, when they expect to have it.