My proposal to test the upgrade is:
- launch the migration for your SOP: All profiles will be converted
- Set a channel upgrade date manually for the full SOP (e.g. in March, but you can change later)
- Pick a company that you want to use for testing (with one or a few computers)
- Change the date so that this company will be channel upgraded the next day
After that you may change the date of the SOP migration to happen faster, or you may want to start by migrating a few companies at specific dates.