I too agree with the others who say to start with one night.
Not sure how relevant this is to this thread, but with Son number 1 (now 34!) it was always best if HE left *US " To explain, if we dropped him off at Grandma's , then drove off, he would get into a right state!
However, if Grandma picked him up from our house, put him in the car & drove to her house, he was 1 very happy chap!
I think it may be a sort of case that if he left us, then of course we were going to be exactly where he left us, but if we left him, he couldn't sort of "place us"
This probably sounds completely mad!