When gaps occur in the FCC database files, you won't show up until the following Sunday's full database update. The FCC publishes a weekly full database file, and then during the week they publish the new and updated licenses incrementally (known as deltas). If their system doesn't generate a daily file and your callsign would have been in that day's file, you won't appear in the next daily file -- you'd show up in the next weekly full database file.
It's a pretty antiquated system, but it works most of the time. The biggest issue is waiting until the next day for us to learn about new licenses. The FCC created an API that allows live lookups, but it's painfully slow and practically unusable. It's easier to download the database updates and host the data in-house.