You can apply to have it set aside at any time. It just means that if you don’t get it set aside before 30 after judgment, it goes live on your file. If it is successfully set aside after that, it is expunged from the record.
READ THIS FIRST - Private Parking Charges Forum guideWhat is the reason given for the judgment? You say that you submitted an AoS. Did you submit an actual defence at any point after that? If you did, and then, you say that you did not submit a witness statement, then that is a different matter.
So, please explain exactly the situation. Did you defend but did not submit a witness statement and subsequently lost the case or did you simply not submit a defence.
Who is the claimant and who, if anyone, represented them? DCBLegal?
Please show us, suitable redacted but leaving all dates visible, the N1SDT Claim Form, what you put in as your defence (if you did submit one), the court order with the CCJ reason and date.
Once we have had a chance to review those, we can advise further.