There have been many reports that the banking deadline is the end of the business day, not the end of the actual day. So, I'd say 8:59 EST is the latest for online. But, I would still not wait that long.
And, if you are on a waitlist, I would call in and see if you have a match that is not processed...that can sometimes take a few days and it doesn't show up on the website like that. This way, if you call and there is no match, you can have the CM bank for you.