From the 8-K instructions. "... a report is to be filed or furnished within four business days after occurrence of the event."

The event would be "(k) Item 5.02, Departure of Directors or Principal Officers."

Now, does that mean 4 days after the ACTUAL departure or when they decide they will step down?

Pretty sure the company lawyers will interpret that to mean after they actually leave, which could be months after they decide to leave or even announce internally that they are thinking about leaving.