Wish I had some expert advice, but I don't. Both my girls sleep with us and if they stand up, I know it immediately as I'm such a light sleeper. This is the only signal they give that they need to potty. Unfortunately, my two regularly get up in the middle of the night to potty. This is with them eating dinner at 5:00pm and having them potty before we go to bed also. Sometimes, they even get up a 2nd time
!!
But at least we use washable pee pads now, so I don't have to take them outside.......