Chatting to a Woking driver earlier today, he said roughly 4am through to 5pm starts and a night turn from May.
He also said 2 to 4 on and 2 to 4 off, but that might be 2 in 4 off, 3 in 2 off, 4 on 2 off. There is a pattern but it is hard to describe without seeing the whole roster.