With a 3m you would need to go out in quite strong wind to jump well. Even then it will be heavy landings. You really need sonething a bit bigger to jump sensibly.
The best way to jump is to have your kite to one side of the window, say the left, then redirect it back towards the zenith while running to the left and away from the kite. As it passes the zenith, if the wind and your tequnique are good, you will jump. Remember to redirect the kite after it passes the zenith.