Upvote:2
Your departure date (2021-12-11 20:00 EST) is 2021-12-12 02:00 CET.
The date of arrival (and departure) on the corresponding passport stamp is what counts.
I don't recall any regulation that deals with any timezone difference between WET (Portugal), CET and EET (Finland/Greece), so assume that the local timezone of the country that issues the passport stamp is what counts.