Eucharistic processions have an honored history in Catholicism. Note the emphasis here on singing:
101. In processions in which the eucharist is carried through the streets solemnly with singing, the Christian people give public witness to faith and to their devotion toward this sacrament.
The bishop makes the call:
But it is for the local Ordinary to decide on both the advisability of such processions in today’s conditions and on the time, place, and plan for them that will ensure their being carried out with decorum and without any loss of reverence toward this sacrament.[Eucharisticum Mysterium 59]
On or near the Corpus Christi feast, the procession is important for, note this, parish or city.
102. The annual procession on the solemnity of Corpus Christi, or on a convenient day near this feast, has a special importance and meaning for the pastoral life of the parish or city. It is therefore desirable to continue this procession, in accordance with the law, when today’s circumstances permit and when it can truly be a sign of common faith and adoration.
The bishop may permit additional processions, or the cathedral may host an alternate observance for the feast:
In the principal districts of large cities there may be additional eucharistic processions for pastoral reasons at the discretion of the local Ordinary. If the procession cannot be held on the solemnity of Corpus Christi, it is fitting to hold some kind of public celebration for the entire city or its principal districts in the cathedral church or other convenient places.
First choice: process after Mass. But it may also take place after a period of adoration, which is how our parish celebrated with Bishop Finn last year.
103. It is fitting that a eucharistic procession begin after the Mass and the host to be carried in the procession is consecrated at this Mass. A procession may also take place, however, at the end of a lengthy period of public adoration that has been held after Mass.
If there are local customs, these should be guiding the procession and its aspects:
104. Eucharistic processions should be arranged in accordance with local customs in regard to the decoration of the streets and the order followed by the participants. In the course of the procession there may be stations where the eucharistic blessing is given, if there is such a custom and some pastoral advantage recommends it. Songs and prayers should be planned with the purpose of expressing the faith of the participants and the centering of their attention on the Lord alone.
I’ve participated in only one of these. Perhaps other readers would care to share their experiences?