[tremon]

Dutch media reports "night from Friday to Saturday", so it's the latter. But that still leaves the open question in which timezone the 11:59 is in (and whether that's a static timezone, or based on local time at departure/arrival), and whether the 11:59 refers to actual or planned time of departure/arrival.

[needmoney04]

Yes, multiple news media reports the ban going into effect on 11:59 pm Friday. Some (e.g., "The Sun") report it as 12:00 am Friday. Unless they give an official answer from the White House, I would not consider either report from news as reliable. "Midnight Friday" can be interpreted both ways until they clarify.