In the Service Level Agreement rule form, select the 'Set to the value of a property' option. Then you can select the property you want to use for the Goal and the property to use for the Deadline. You can configure a different activity for each event.
In the SLA we can refer only the date time properties. Before this SLA gets triggered these values should be set as part of the work object else the SLA will not be triggered properly. Once the Goal Time is reached as part of the escalation process the Activity will be triggered. Once the property is configured select the Run Activity action from the Select Actions against Goal and Deadline configuration.
Please find the attached screen shot for your reference.