Leave at 7 (or half six if you're like me!) and you should avoid the worst of the jams - still expect a bit of a queue in! And watch your speed, the Bill like to get up early on Revival weekend with their cameras.
I arrived at 06.45 this morning and the queue was starting. The carparks (fields ) ars already a mud bath beware as its tricky arriving and will be worse leaving both mud and queues