Lev 23: 9 The LORD said to Moses, 10 “Speak to the Israelites and say to them: ‘When you enter the land I am going to give you and you reap its harvest, bring to the priest a sheaf of the first grain you harvest. 11 He is to wave the sheaf before the LORD so it will be accepted on your behalf; the priest is to wave it on the day after the Sabbath.
Lev 23: 15 “ ‘From the day after the Sabbath, the day you brought the sheaf of the wave offering, count off seven full weeks. 16 Count off fifty days up to the day after the seventh Sabbath, and then present an offering of new grain to the LORD. 17 From wherever you live, bring two loaves made of two-tenths of an ephah of the finest flour, baked with yeast, as a wave offering of firstfruits to the LORD.
The Complete Jewish Bible here offers us an excellent translation. Let us compare and contrast Leviticus 23:10 with Leviticus 23:17. Leviticus 23 is frequently translated as firstfruits, as opposed to the translation we see here sheaf of the first grain. In Leviticus 23:17 we see the wave offering of firstfruits. There is quite a bit of confusion about the idea of firstfruits in both of these verses. In verse 17, the Hebrew is quite clear. The term used that is translated firstfruits is Bikurim. In fact, the term Bikurim is used to indicate the firstfruits offering throughout Scripture. The term used in Leviticus 23:9, is quite different. Instead of Bikurim, firstfruits, the terminology used in Hebrew is, Omer Reishit, which literally means first sheaf. So we see that the Complete Jewish Bible translation of this verse as, “sheaf of the first grain,” is a far better translation and understanding than firstfruits. This frequent but poor translation has led to much misunderstanding of the verse. As you can see, Leviticus 23:10 is referring to the first day of the Omer. Leviticus 23:17 is referring to the Moed of Shavuot. This is why Shavuot is sometimes referred to as the Festival of firstfruits. The beginning of the offering of the firstfruits is Shavuot. The Mishnah explains in tractate Bikurim that the Bikurim (firstfruits) were offered beginning in Shavuot, all the way until Hanukkah. No Bikurim were offered before Shavuot. In this way, Shavuot is the Festival of firstfruits.
In Yeshua’s time, the day that the first sheaf wave offering, that is the first day of the Omer, was the 16th of Nissan. The Pharisees controlled the Sanhedrin, the Nasi of the Sanhedrin was Gamliel, so Pharisaic interpretations were used in Temple ceremony, such as the counting of the Omer, and the Nisuch haMayim, the water drawing ceremony. It was not until after the counting of the Omer was finished on Shavuot that the Bikurim were brought to the Temple. It is easy to see that in no way can firstfruits be associated with Pesach.