I also planted trillium. I got them from American Meadows, IIRC.
I planted them two years ago and saw nothing and thought they had died.
This year, they ALL came up and about half flowered. I also found some wild trillium on our property, but have no intention of moving it. It’s going to stay were it is and do it’s native planted thing.
I have two native trillium that have come up. I’ll be doing the same thing with them. Let them do their native thing.