Stevia is so fricking hard to get started!!!! Looks like only 1 of the ~9 that had germinated might actually be taking after having been moved from PT to soil -- I think all the other 8 are kaput.
So, today, the next round of seeds that popped in PT, today, instead of putting them into the soil mix, I put a layer of vermuculite on top of the soil mix, then carefully placed the popped seeds, then just a few pieces of vermiculite on top. I'm not sure if they'll be able to grow fast enough to reach the soil/nutrients before going kaput, but, this is at least worth a try. There's quite a bit of vermiculite underneath them to provide buffer re: fungus gnats -- might be too much distance for their roots to travel to nutrition but we'll see.