Cancellations are made months in advance, but airlines hold out on telling the passengers until the moment when they can cause the greatest inconvenience.
Sorry all tongue in cheek.
Seriously though it all depends on the situation, if there is a cancellation which is made the day or a few days prior it gives airlines plenty of time to make alternative arrangements for the passengers.
When a cancellation is made last minute that's when you'll probably run into a few problems. I'd suggest you contact the airline again the night before or on the day of your flight to make sure everything is running to plan.
A320.