Hi layton12360
I've heard of someone being offered one on a Saturday - but never Sunday before. I had a look at their website and there's nothing about the days they do assessments.
If, by any chance, something goes wrong and you have to change the appointment, I think you would have a good case for arguing with the DWP that the first offer doesn't count, as it was unreasonable. Make a note of everything that has occurred just in case you have to raise it as an issue.
Hope your assessment goes well.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems