Serengeti Migration

A friend and I are planning a three week trip to Kenya. At present we are intending to fly out on the 20th October and back on the 10th November. Does anyone know at this time of year where we would be best able to see the migration? From the websites I have looked at, I understand that the migration may be on the Masai Mara or starting to heard south. Is this correct?

If anyone is out in Kenya at the moment and so has up to date information on the migration this year, I'd be extremely grateful. This is a holiday we've been talking about doing for many years and so I would like to give ourselves the best chances.

The dates I have mentioned above are not set in stone and we would definitely move them if it gave us a better chance of seeing the migration.

Thanks!