I have a boundary timer event for which I need set the timeDate based on some input conditions of the individual task instance. Looking through the API's I'm not seeing how to do this. The users guide only covers setting date, duration, or interval statically through model.
You can use an expression in your timer-definition, using process-instance variables for example. Or for more complex calculations, you can always call a method on a bean (eg. timeService.getDueDate(execution)) using spring or the special "beans" list on the process-configuration.
A third option is to calculate the date in an execution/task-listener or JavaDelegate on service-task and set as process var to be used when needed…