Hi Mark,
It needs to be with them in time for the date that is on the actual form. So for example - return by 2nd May 2025, make sure they've got it, if you can, by the 1st of May, so that it can be scanned straight into the system.
Hope this helps.
If you're struggling to meet this time, I would call again and ask for a further extension.
Chris.
Nothing on this board constitutes legal advice - always consult a professional about specific problems