The award date
Your award date is the date you first got the level of priority that put you into your current rehousing band. This might be the same as the 'registration date' when you first registered for rehousing - but not always.
Your award date can be different to your registration date if you go into a different priority band because your circumstances change, or because the housing rules change.
If two people from the same priority band want the same home, it goes to the one with the earlier award date. If they have the same award date, it goes to the one with the earliest registration date. So the earlier your award date and registration date, the better your chance of getting a home.