Once you have passed your level 2 qualification to become an MOT tester, you must successfully complete and pass a demonstration test (on a vehicle of testable age) within 6 months of your qualification date.

If the request for a demonstration test exceeds 6 months and up to 5 years from the qualification date, the current years MOT annual training and assessment (as well as any additional training) must be completed prior to the demonstration. Should this period exceed 5 years then they will need to re-attend the initial level 2 qualification.

Source: MOT Testing Guide Appendix 6.1 (Candidates to become a tester)