When is the MSN allocated to aircraft?

We typically allocate the MSN (Manufacturer Serial Number) to our database at the aircraft's first recorded flight (First Flight Date), however it can be earlier in the case where an aircraft is registered prior to leaving the assembly line.

A virtual serial number may be assigned to undelivered aircraft. You can use FG ID to track individual aircraft. The FG ID is unique and not recycled. But once the aircraft is delivered the serial number will change to the OEM serial number.

There is no precise time when we add the serial number; it is added as soon as it is made available from our sources. All serial numbers for new aircraft are verified from monthly delivery reports supplied by the airframe OEMs.

What is the FG ID (FGID)?

https://helpdesk.cirium.com/hc/en-us/articles/360036552171-What-is-the-FG-ID-FGID-