You usually only get a couple of days' warning but in recent months we have had:
15th November
5/6 December
17th January
18/19 February
20/21 March
So - I hope the trend will continue . Of course I am always caught unprepared and never manage to list all the things I had hoped to... I must dig out some more stuff this weekend and get photos done and descriptions written just in case we do get another one this month!