Since the pasuk is “shevah shabbosos temimos tehyenah” why aren’t we required to make each one of the weeks complete? So if the 8th day of the ommer is Shabbos it should be assur to make early shabbos since this is cutting off the end of week 1.
A- Maybe the difference is that bringing in shabbos early does not conflict with the temimos of the past weak, since shabbos is unrelated to sefirah, as appose to shavuos which defines the end of day 49.