As cjoseph mentioned, by default AirMatch pushes its updates once a day (if a change is deemed necessary). By default this occurs at 5am. You can change that time if you want.
You can run an "on demand" optimization via the MM cli.
airmatch runnow <option>
The options are:
full (the same full optimization algorithm that runs daily)
quick (a "quick and dirty" scan of random channels to compute an updated EIRP)
incremental (only works on new APs added since prior full run, while keeping existing settings on existing APs)