The water competency certificate was requested at the AD on July 6 for me. They did, however, tell us not to be worried if you were missing something. It could be collected later. I think that it would be best to take it though. Things like RSA's and 1st Aid, that cost money, are probably OK to put off so that you don't outlay that expense until you are approved. It definitely looks good if you have everything that they require on your AD. Makes you look keen!
ON A SIDE NOTE .. any one from the July 6 AD had their references contacted? I received the email saying that I had been progressed to reference checks on Thursday but they haven't contacted them yet. Just curious!