They do all happen at the start of a turn, I haven't logged if there is a specific order yet, but here is a sample of starting a new campaign and playing IIRC two turns (with one autoresolved battle, no actually played battle):
As you can see, all the slots and factions start their turn before the Camera mover starts (the one right at the start that shows you around your empire and tells you what you should do in the campaign), and it's not until the autosave gets saved that turns end for a (my?) faction.