The clock always runs from file date to file date.
If you received a chapter 13 discharge, you can't get a chapter 7 discharge unless 6 years runs between the filing of the chapter 13 and the filing of the chapter 7, UNLESS the chapter 13 paid at least 70% - 100% of unsecured creditors, depending on the situation.
The 4 years is for getting a chapter 13 discharge after a chapter 7 discharge, not a chapter 7 discharge after a chapter 13.