>>2054927
https://www.youtube.com/watch?v=O72RviRJszU&t=1568s

You start a "colonial charter" in a province (group of locations) and that will continue moving a few pops from a province you select until you stop it.

A province is owned by you when it has
1. At least 1,000 pops.
2. At least 50% of pops in the location are an accepted culture and religion.

So the fastest way would be to colonize locations with 500 pops, as then you'd only need to send 501 to gain control of the location.