Calculate the amount of time needed to the map load?

So i will make a GUI that will show up when a map is being loaded. How do i calculate the amount of time needed to the map to load?

Well, say you were loading a map, each brick was, 0.5 seconds to load, because of a script.

So, say you had , 1000 bricks, for your map.

So, in 1 second 2 bricks loaded, 2 divided by 1000 you have 500 seconds to load your map.

Now for your GUI, I could suggest you add a timer, counting down from 500, or whatever time it takes to load the bricks.