Flight Time of Object

Let's say I have got a ball, to which I apply some Force to let It fly in an arc. How do I precalculate when the ball will hit a collider, to be more specific, I already calculated several points along this arch(let's say 100) so I have got the total Distance the ball will travel. I also know where the ball will land. The problem is, near the top of the arc the ball will travel slower due to gravitation and so on.
How could I determine the time It takes for the ball to make the full arc?

 

There you go:

Trajectory of Projectile: Time of Flight.