The Timing When the Board Rotates Most Easily (Physics)

Let’s represent the force applied by the front foot with a blue arrow. When the board is stationary and has no force acting on it, you need to flick the board using only that blue force. But what if the board already has an upward force indicated by a red arrow? In that case, even a very small force from your foot can generate enough force to flick the board. This shows that the board flicks effectively when it generates upward force and you flick your foot in the opposite direction.