What about the ordinary? Any Latin? And does the priest sing his parts or speak them?

I've been doing the same kind of project for almost 6 months now. I honestly didn't go super slowly because I am who I am and so is my pastor, haha, but here's what I've got from my limited experience up to now.

- I worked first from adding things rather than replacing them. I haven't yet added an Entrance antiphon, I've just done the Communion antiphon, and we've also added the Marian antiphon at the end of Mass after the final blessing and St. Michael prayer, then followed by the recessional.

- The pastor is leaning into chanting more and more of his parts, which I think is really key. I think it's important to tune people's ears to chant as being an integral part of the liturgy in that way. I've worked on some specific chants with him like the Exultet, and am planning to work on chant with the deacons as well. I'm also personally part of the Ordinariate (the church where I am DoM is diocesan) and one of our last pastors valiantly struggled through the massive amounts of chant despite a pretty shaky grasp of the pitch, and it was fine. You just lead the community's chanted responses really strongly to help.

- Timing some things with liturgical seasons can be helpful, but I think it would be good to go one thing at a time as far as the big things. Chant propers instead of hymns will feel huge even if it's an addition rather than a replacement depending on your congregation.

- I've never been a big fan of taking up time before the Mass begins to announce or teach something, but the congregation at this parish is responding well to it. This particular parish likes a lot of catechesis, teaching, etc. So when I introduced the Marian antiphon, I gave a short (like, one or two paragraphs) explanation of the history and then sang through it with everyone. I've also gotten good feedback from things like bulletin announcements and Flocknote columns--for the latter, I've been giving a short introduction to one of the hymns I'm using that weekend that I think people probably don't know, then include text and a recording for people to familiarize themselves.

- I still keep some of the folksy music here and there and try to use as much familiar music as I can. The parish has used Breaking Bread for years and I actually downloaded the index as an Excel spreadsheet and have been working through various columns: talking through the Faith Formation coordinator who has been here a long time to get a sense of what music is familiar to the parish, what they know very well, etc; looking at getting the same kind of info from other people; and also including a column for me where I note if something is a yes with no reservations, yes for now, maybe, absolutely not. I find people do know at least *some* traditional hymns, and for the rest I spend a good amount of time figuring out which ones I'm still willing to use. I went a little too hard with just more traditional hymns for a while, but I think if I had kept going slowly and continuing to use the less offensive OCP stuff I would have been able to transition more smoothly.

Some other observations: my experience has been that there is a small minority who are really opposed and are even likely to leave to seek out what they're looking for; a lot of those people can't really be reached easily. There's another small minority (maybe larger than the other group) who has been hoping for these kinds of changes and are excited for the reverence they signal. The much larger majority group is in the middle, ranging from upset but kind of open to just politely confused. I think those are the people you target--understanding why things are changing, that there's a reason beyond just personal preferences, and that there's a desire to conform more to the spirit of the liturgy and to the directives of the Church, helps a lot to sway them. But there's also a lot of deeply emotional attachment to the particular musical style so it helps to go slowly in order to get people used to the idea.

The idea of adding instead of replacing is very sound advice. In order to make sweeping changes, you typically need to cater to everyone throughout the process. And it is a long process.