In the Old Covenant there were six yearly feasts and these six feasts had seven holy convocations. If you counted the Passover as a holy convocation, you would have eight. The first of these was the Passover feast on the 14th day of the first month which is very close to the time that Easter is celebrated today.
The communion service is a sacred ceremony, a symbol of the sacrifice on Calvary referred to by Paul, as “Christ our Passover sacrificed for us” (I Corinthians 5:7). The sacrifice on the cross at Calvary is the real Passover which we commemorate every time we participate in the communion service and this is not commemorated just once a year.