Last year, the summer schedule 2005 was released in november. Easyjet usually releases the schedule in several parts, e.g. one day all routes from London-Stansted, the other day all routes from Berlin.
Therefore it's a good idea to subscribe to the newsletter.

Regarding the fares: as long as you book in the first days after the release, it is very likely to find very low prices for every route and date, except holidays like easter etc.