You can usually anticipate when a Daimyo is going to move by a few ways:

1. He suddenly appears from out of his castle.
2. A neighboring province is either low on defenders or has none at all (you can sometimes bait a Daimyo by abandoning/weaking a province next to the one he occupies). Take notice of when his banner neighbors ronin provinces.
3. You have noticed the Daimyo move a few provinces already - usually when the older Daimyo is killed and an heir is situated in the back when he takes over.