It is his duty to ensure that the groom arrives at the place of the ceremony at least 20 minutes before the ceremony is due to start. He also has to ensure that the ushers are ready and suitably dressed, they all have buttonholes and the order of service sheets are ready.
He must collect any telemessages or cards for reading at the reception and most important he must keep the rings safe until they are needed in the ceremony.
But well before the wedding he will discuss the wedding with the bride and groom and chief bridesmaid. At this meeting he will help choose the ushers.
Later he will help organise the stag party. Do not forget that every stag night must have a prank.
Well before the date he must start preparing his speech for the day.
He will attend the wedding rehearsal liase with the ushers on final arrangements.
He should check on the details of parents and family of both bride and groom so that special arrangements can be made for their seating.
Most important arrange for transport for himself and the groom to get to the ceremony venue.
At the reception then stand in the receiving line to greet the guests and if there is no toastmaster then announce the speeches and cutting of cake.
After the bride and groom have finished the first dance the groom will then start the next dance with the chief bridesmaid and that is the cue for the rest of the guests to get up and join in.
He is also responsible for organising the decorating of the going away car.