When is the feast of first fruits

According to one web site I Googled, it is on April 4th, the Sunday after the Shabbat following Pesach (Passover). Outside of that one, I could not find any other reference to the date.

if you count 50 days from april 4th, shavuot (pentecost) should be around 24 may. yet most calculate shavuot to fall on 18 may sundown (most scholars have fixed shavuot to fall on 6 sivan). so i'm a little bewildered too.

According to some Jewish traditions, The Feast of Firstfruits (wave offering of the Barley Sheaf) should be the first day following the Feast of Unleavened Bread. The passover meal (Seder) is consumed after sunset on 14th Nisan (Tuesday 30 Mar 2010), Feast of Unleavened Bread begins at sunset 15 Nisan (Wed 31 Mar 2010) and starts and ends with a ceremonial Sabbath (do not confuse with the weekly sabbath). The Feast of First Fruits should be the day following the first day of the Feast of Unleavened Bread or 16 Nisan. In 2010, Counting 7 weeks from the Wed 31 Mar 2010, Shauvot should be Wed 19 May 2010).

The timing according to many evangelical Christians is the Feast of First Fruits should be the day following the normal weekly sabbath after the Feast of Unleavened Bread. That would make Sunday corresponding to Easter the Feast of First Fruits corresponding to perfect fulfilment of types according the Apostle Paul's writings. I believe that the timing of the Feast of Unleavened Bread is all about the ripe Barley harvest, so Jesus resurrection could have fulfilled the type without being the exact day.