When exactly are the faithful supposed to approach the Communion rail?
Immediately after the priest genuflects after receiving the Host, immediately after he genuflects after receiving the Precious Blood, at the second Confiteor, immediately after the Misereatur vestri, or immediately after the Ecce Agnus Dei…Domine non sum dignus?
I've seen choristers approach it immediately after he genuflects after receiving the Precious Blood, elderly people approach it immediately after the Misereatur vestri (because it takes them longer to walk to the rail), and all other parishioners immediately after the Ecce Agnus Dei…Domine non sum dignus. Surely there are rubrics on when the faithful should approach the rail, aren't there?
John Nolan commented on a "Fr Hunwicke's Mutual Enrichment: The Roman Rite of 1965" blog post:
No-one ever approached the rail until after the Ecce Agnus Dei. From 1967, when the Ecce preceded the priest's Communion (as in the Novus Ordo) a bell was rung to signal the people to approach the rail. That is probably why some people nowadays interpret the three bells at the priest's Domine non sum dignus (wrongly) as a signal to come forward.