Is it possible to move full screen apps in Mission Control to be at the beginning, (before space #1)?
No, you can't. The only way to achieve some kind of manual ordering is disabling the "Automatically rearrange" option in the Mission Control prefpane, and switching all your apps to fullscreen in the correct order from left to right (new spaces get added to the right).
That said, you won't be able to move anything left of the first desktop space.
I think the sequence depends on how frequent you use the Desktop and the full app.