Help provisioning 2 Gbps fiber for UniFi UDM-SE

Hi, my new 2 Gbps Xfinity fiber service is scheduled to be activated on November 16 and isn't active yet. I'd like to connect the Ethernet output from the fiber ONU directly to the WAN port on my UniFi Dream Machine Special Edition (UDM-SE) and use it in place of the XER10 gateway.

I've seen other threads here where Xfinity employees have helped customers get their ONU provisioned for a customer-owned router. Can this be arranged ahead of my activation date, or will I need to wait until the service is active?

Please let me know what information you need and when I should send a direct message. Thanks!