There is a quick check to see if the tenant has been moved to the standard CSP platform.
Go to your customer's Office 365 Admin Center, click on the "Settings" icon and go to "Partner Relationships"
Once the syndication partner is listed as a "Cloud Solution Provider" then the tenant has been moved out of the syndication platform. At this stage you're ready to transition them to your 2-Tier CSP of choice.
If the syndication partner is not listed at all in the Partner Relationships area this means that the customer is still on the syndication platform. You need to raise a prioritization request to move the tenant from Syndication to CSP earlier.