I wouldn’t worry too much about stressing on where exactly you flick - that motion comes quite naturally to your body shape and it varies depending on how you place your feet when setting up. But generally speaking, you want your front foot to flip the board just to the side the nose - imagine the dead centre of the nose is 12 o’clock. If you’re goofy your front foot should be aiming for 1 o’ clock when flicking. If regular, 11 o’ clock. Flick your front foot at this angle and upwards (not towards the ground).
When I was learning it helped by holding on to something to stabilise and lift myself up in order to focus purely on just how to flip the board properly - best is if you can find something like a flat railing to rest your hands on at about chest height.
But others are right - doing the trick whilst moving is actually easier in terms of distributing balance and generating momentum for the board to flip properly.
Just practice. Don’t worry too much. It comes naturally.
