Well, you are in for an unpleasant surprise. I hate being the harbinger of bad news.
It takes 3 - 5 months after test is set to "Completed" (approximately) to receive an oath date (oath notification). Now, this oath date could be as far as 6 months in the future FROM the date of oath notification.
For example, if your test status is set to "Completed" yesterday (September 17th, 2021), you might receive a notification in your status dashboard on February 17, 2022 saying "Congratulations! You've been scheduled to attend your citizenship ceremony on August 17th, 2022."
Please note that this is based on a worst case estimate (sort of), things could happen sooner than this. For someone who passed their test on September 17th, 2021 for example (depending on when the applied), they could receive an oath date, for say Feb or March 2022 (if they get lucky). This also depends on the local office of the applicant.