Sunday, the first day of the week Jesus rose from the dead, the Lords day. 40 days later Jesus ascended to heaven on Wednesday, wedding day. 10 days after Ascension and 50 days after Resurrection Pentecost fell on the Church on Saturday, Shabbat, the Lords rest.Good article at Charisma.
https://www.youtube.com/watch?v=EZvOgmr0oVIWhy the Church May Be Ignoring the Powerful Significance of Pentecost