Since the Hebrew day starts at sundown Good Friday, the first day, would have started Thursday evening. From there you get Saturday as the second day and Sunday, the day used by the earliest Christians to celebrate Christ’s Resurrection, ad the third day.
As to the name - while some folks think that English was the official language of the ancient world it wasn’t. Come to think of it, English wasn’t even the official language of the Church. Why is this important? “Easter” is an English word. In many languages, if not most, the Feast of the Resurrection is named after the Hebrew word Pesach which means passover. In Latin, the official language of the Church for centuries, the word is Pascha. So the fact that the English word may have been derived from a germanic goddess of the spring equinox means pretty much nothing at all. (I, personally, do not think Easter is named for the goddess but rather for April which was Eostremonat. Whoever decided to use the name “Easter” was probably thinking that passover is usually in April and that is why they went with that name—not because april was a month dedicated to the fertility goddess, Oestre.)
By the way, in some light research, I found that Eusebius noted that there were problems with the timing of the feast of the Resurrection around 190ad. This had to do with the Church’s celebration of the Resurrection as related to the Jewish celebration of the Passover. So, the issue was clarified by the Council of Nicea in 325. I think we can be confident that it was not called Easter by the Eusebius nor by the Council of Nicea. Nor do we have any reason to believe that the Feast had anything to do with a germanic pagan fertility goddess, since the Feast was well in place prior to the conversion of the germanic people’s associated with that particular goddess. The first hints of Christianity among the Germanic people was in about 337. And, as far as England, who borrowed the word from the germans, they didn’t convert until even later (according to Bede; the same source who tells us about Oestre)
Bottom line, the Feast of the Resurrection was in place at least in the 2nd century (probably was celebrated from the beginning). The germanic worship of Oestre would have had no bearing on the “creation” of the feast as the germans had not even been converted yet. I also don’t see any germans as attendees of the Council of Nicea either but perhaps I am mistaken.
Either way - Enjoy the celebration Lorica - no mater when you celebrate it.