Thank you for all of your responses.
My immediate reaction was 'no way' when I found read that someone was having this done in one day, but then questioned myself because I'd not ever had to wonder about it before.
I too would recommend anyone to find a different vet to be honest as I personally don't think it shows a good understanding of the whole stress/immune system issue that we owners face with rabbits. I don't really care if it's possible, but it's whether we should be doing this.