How far in advance should I order my cake?

Generally I would recommend six to 12 months in advance so you can have your special day booked into your cake provider's diary before someone else does!  That also gives you peace of mind so you can move on to all the other things that have to be organised for the perfect wedding day.  If you advise them up front then the cake provider should be able to incorporate at least colour scheme and perhaps finer style elements into the cake design later once you have decided on other aspects of the day like dresses, flowers and the decor of the wedding venue.

Having said that you can always approach a provider at any time as you might find they are able to fit you in.

It's hard to say as every supplier is different but it's good to get in touch and start looking 6 months in advance. Then you can secure the date and still have some time to cake-test and find the best flavour and design for your day :)