What I have noticed, for some reason is that ALL my emails from track, telling me that there has been an update on ucas arrive at 12.01am on the dot [as the timestamp is on the email itself]. This may be the time when they have programmed it to be sent out, but none of my replies [5 out of 5] have been any other time except 12.01am lol. Even though some offers may already be on ucas, you wont be notified till 12.01am.