The trigger for a cannula change for me is either pain at the cannula site so discomfort when I move, or if my levels are rising as this can also mean a dodgy site, as your ok and levels are ok, then it's not worth changing tonight.
I personally have no issue changing my set at night time as I use steel sets so know they are inserted and pump has an alarm if there is a block on my 640g which would wake me (eventually) if I was asleep, only happened once in 2 years though.