Of course they had never heard of the word "Easter".
If you mean to claim that the early Christians didn't have a special celebration commemorating the resurrection, which they called (if they were Greek speakers), pascha, then I should point out to you that there were disagreements over the date on which Easter (Pascha, Pesach, Passover) was to be celebrated before the last apostle had reached room temperature. Google "Quartodeciman controversy".
Easter (or Pascha, if you prefer) is the earliest distinctively Christian celebration we know of, except for the celebration of Sunday as the Lord's Day.
Another tender spot. Another celebration Christ (or his disciples) didn't celebrate. I know , I know they met on the first day of the week (as well as other days of the week). If Christ is our example - why don't we follow His example? What day is the Lords Day pray tell? Hint see Mark 2:28. Also I understand the change from Sabbath to Sunday was early on in the churches history. With no Biblical reason. If we love Him - we should do what? Hint John 14:15.