My vets say 8pm, although I often do it a bit later, but only cos I know my vets schedule - that is one thing to bear in mind Mark, your vet might not operate till the afternoon, but not all vets do. Mine consults till 10.30, unless she overruns, then does the ops, cos she has to cover lunch at the other surgery some days. I have never noticed the bit about not taking up water until recently, I think it was Rolo's dental (I never ask for instructions, and they know I know them) that I finally re-read the instructions, so have never done it. I have had blood tests cancelled due to me forgetting and feeding them though.