We struggle to define all of existence, so we have no frame of reference to speak for Existence.

What happens before birth (or conception really) is a Mystery.

I believe in anticipation though. A dog may bark in anticipation of owner returning home, before they come home or not.

So you need a frame of reference to speak of. If it's all bounded outcomes are certain. But nothing pragmatic is ever perfectly bounded..

Notice that Free Will doesn't imply we always get what we want!