It depends on the purpose of your model.
Business oriented process orchestration
For orchestration between several tasks/activities of several applications of a complex process, you could use Business Process Model and Notation (BPMN), which is a standard of the OMG.
There you can model event-based "gateways" to control flow of control or "messages" between activities. An event could be in your case a timer or a error (e.g. time-out errors) depending on the desired emphasis.
Remark: THere are several third party tools that use BPMN models to generate BPEL in order to to make the modelled process orchestration exectutable.
Technical model
If you want to show interaction between applications, but not necessarily modelled as business processes (user perspective), you could also really consider UML:
- activity diagrams can present event actions and also timers
- eventually, sequence diagrams could present timing constraints and conditions. But intuitively I doubt it's the best choice for your question here.