I want to think these took between 14-21 days to germinate. Not all seeds germinate at the same rate, and not all species of hosta, either.
What worked for me was: sterile seed starting mix, bottom-watered seed starting cells, those water wicking mats (to keep them moist; they like moist) and bright fluorescent lights left on 18 hours per day (I've read that some people leave them on 24/7.) I didn't use heat mats (but they might have helped). I did keep my room temperature warm.
I remember thinking it was taking forever for them to get going. It's a slow process. The babies in my photos were started at the end of January and that's all the bigger they are. They're still in 2" pots (although if I don't plant them out I'll pot them up to 4" soon, but I'm leaning toward getting them in the ground). Once they take off they do grow pretty quickly, but it takes them a while to get going.
Good luck, Angel!