I do not know where you live. One name for the Holy Day celebrated on the 50th Day of Counting the Omer is Shavuot. Shavuot was the day after the end of the seventh week of Counting the Omer. Where I am in the United States of America it was two days. In BAMIDBAR/NUMBERS Chapter 28 Verses 26 through 31 we learn about Shavuos, beginning with "On the day of the first-fruits," if I understand this correctly as it is in my Chumash.
I do not observe Saturday.
Most folks who celebrated Pentecost did it on the Sunday 20th May. The same folks celebrated Passover on a Saturday 7th April, 7 weeks prior. Most folks believe the count starts "on the morrow AFTER the (annual) Sabbath". But the greek and Hebrew state that the count starts on the Sabbath morrow/morning, not the morrow or morning AFTER the Sabbath.
For most who don't celebrate Pentecost, this all sounds very technical.
Lev 23:11
And he shall wave the sheaf before the LORD, to be accepted for you: on the morrow
after the sabbath the priest shall wave it.
Lev 23:15
And ye shall count unto you from the morrow
after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete: