We strongly advise you to book a photographer for your wedding as soon as you can. The good ones get snapped up quickly!
In years to come, memories of your big day will be very precious, so don't skimp on quality. Your main selection criteria? Simple: if you like him or her, book them. A good rapport with your wedding photographer, in addition to your preference for their previous work and photography style plays a key role as well. Listen to your gut instinct here.
Discuss pricing options to check what's included. Image rights (the use of the pictures elsewhere) may need to be taken into consideration, along with the provision of digital images and the inclusion of an album and so on.
Do take up an offer of a pre-shoot / engagement shoot if it's offered. This will enable you to get to know your photographer and relax in front of the camera, for them to understand your relationship dynamic and importantly, what you are looking for.