When did you realize your role had changed after your parent came home from the hospital?

My dad came home directly after a short hospitalization with medication changes and a new regimen to manage.  My mom is still living at home together, but i cannot count on her as she starts forgetting things.  My sister also lives more than two hours away, not helping when one of the child has ADHD, so a lot of the responsibility has gradually started falling on me from a distance.  Mom keep trying to play it like nothing happened.  

For others who have been through something similar, when did you first realize that your role had changed from simply checking in to actually becoming much more involved in caregiving?

Was there a specific moment and trigger, event that made it clear to you?  what do you do to support in your case?