The Archdiocese of Boston tells us to say “forgive,” and this is part of a campaign to get Catholics to go to confession more often. Even so, it appears that “bless” and “forgive” are both used in many places, and I’m glad I remembered my 1947 instruction correctly!
thelightisonforyou.org/confession/index.html
"Making a Good Confession
Going to Confession
The penitent and the priest begin with the sign of the Cross, saying:
In the Name of the Father and of the Son and of the Holy Spirit.
The priest urges the penitent to have confidence in God with these or similar words:
May the Lord be in your heart and help you to confess your sins with true sorrow.
The priest may read or say a passage from Sacred Scripture after which the penitent then states:
Forgive me, Father, for I have sinned. It has been (however many days, weeks, months or years) since my last confession."