The music should be in full swing and evening guests should be arriving. 

When the time comes to leave there are two forms of exit, one where everyone forms a circle and the couple go in opposite directions and thank the guests.

The other the guest's form an arch and the couple go through. If you still have your bouquet, this is the time to throw it over your head to the single ladies, and the one to catch it, is the next to marry.

A good time to check the taxi is early in the evening, just to remind them and satisfy you that all is well.  Many a time I have given a lift to the Bride & Groom back to the Hotel, as the taxi did not seem to have any record of the booking.