I guess I should say they did use the plate at night... the nights would still get cooler.... but I took it completely out of my brooder box at 4 1/2 weeks. They were feathered out by then.
Im trying to remember how high mine was at 2 weeks.... Im thinking that the front was maybe 3-4 inches high and the back was maybe 2. That way they can decide where they want to be placed under and how warm they wanted to be. My chicks were completely done with it at about 3 1/2 weeks... only...