Contrary to what many Armenians have been led to believe, and contrary to what appears to be the accepted practice, it is not proper habitually to arrive late for the Divine Liturgy. The Badarak is a sacramental under- taking that has a beginning, a middle and an end. There is a logical flow to the ceremony. A person who arrives at the opera at the third act not only has to struggle to get her bearings in the middle of a complicated plot, but she has also missed a lot of good music in the first two acts! People who habitually arrive late for Badarak make it all the more difficult for themselves to derive meaning and inspiration from the experience, not to mention benefiting from its intended results.
But the Badarak is not only— not even primarily —a matter of attending to one’s personal spiritual needs. The Divine Liturgy is intended to bring us into Communion with Jesus Christ, the Son of God and through him to bring us into communion with one another. Jesus gives himself to us in Holy Communion so that all those who have received Him in the Bread and the Wine will bind themselves to one another in forgiveness, humility and love. Holy Communion is the glue that holds the Church together. People who do not make the effort to engage themselves fully in this awesome sacrament, as, for example, by habitually arriving late, interrupt the divine process of cultivating love and unity within the church parish in Christ. Arriving late for the Liturgy can actually be hurtful to the clergy, altar servers, choir, and to all who try to attend the Liturgy earnestly.
Of course when one is unavoidably prevented from arriving on time, he or she should not hesitate to enter the church quietly, find a place, and join the Badarak already in progress. Those who have arrived after the start of the Eucharist proper (anytime after the deacon intones, “Mee vok herakhayeets”) should not approach the altar for Holy Communion. He or she should speak with the parish priest after the Divine Liturgy and, if appropriate, request to receive Holy Communion from the reserved sacrament.
Source: Frequently Asked Questions on the Badarak, The Divine Liturgy of the Armenian Church by Michael Daniel Findikyan.