Craft Commerce starting order ids form a higher number? Is there a easy way to start Craft Commerce order ids form a higher number?
So the can follow on from an old system and not overlap?

autoincrement in the DB table maybe?
You can write a Craft plugin that listens to the onBeforeOrderComplete event and implement whatever sort of order number format your business requirements require.

Alternatively here's an existing plugin that uses that method that might already cover your needs: https://github.com/bossanova808/CommerceFriendlyOrderNumbers