No problem! Enrollment date should typically be the date you add the person to the program/start tracking them. We use it as the date of recruitment/registration (for multi-session educational groups) and others use it as the date they come to the clinic to fill out new patient paperwork, for example. The program stage has an event date that documents the actual date of the encounter. Program stages can also, optionally, have a “due date” (which I usually hide unless I am wanting to schedule reminders). Due dates are how you would automatically schedule events.
Incident date has always been a bit confusing for me, not working in clinical settings, but it has to do with a date you know at the time of enrollment that you want to use to calculate subsequent stages. Like if you enrolled a person Monday, but you know their last vaccine dose was Saturday, and you want to schedule their next vaccine dose from Saturday rather than Monday (or something). I usually turn off the incident date in program configuration because it’s not really relevant to the type of work we do. See this post for a better explanation: