I get a letter almost every time I buy something saying that the sorn had expired and it was an offence bla bla bla
But I always send/email the sorn a couple of weeks after the v5 was sent otherwise you get it back saying its not in your name and its usually in the same post on the same day lol
Least these days you can email it but same thing goes
You sorn it and the message appears about an offence etc
The last keeper should sorn and you should soon as you can and the system allows but don't sweat it within a month I guess