This video explains why we should NOT wait for the barley in the land of Israel to be ready to harvest before we declare the new moon of the aviv. Rather, we should declare the new moon of the aviv when we know that we will be able to bring a sheaf of aviv or carmel barley to the priesthood in that (coming) month. It also explains why, if we do NOT do it that way, it will eventually cause the farmers with the earliest ripening barley to lose their crops.
(One correction: aviv barley is medium dough, not soft dough! But the rest of the study is correct as of 2021-02-05.)
Click here to read the full written study on “Why the Omer (Should Be Brought) Before the Harvest.“
Click here to read the full written study, “Aviv Barley and the Head of the Year.“
This is the Karaite article referenced, “Harvestable Fields Required for Yom HaNafat HaOmer.“