Traditionally, etiquette dictates that the bride and groom spend the night before the wedding apart. If they decide not to, then they should set off early on the morning of the wedding to where they will each be getting ready.
The bridesmaids, best man and ushers must be at the bride and groom's respective locations in plenty of time if they have not been there the night before. It is best only to have the key players around at this stage; too many people milling about makes it difficult for everyone to get ready.
Never underestimate how much there is to do; it is always sensible to allow extra contingency time for last-minute crises and delays.