I think that if you’re significantly sore the next day you might be pushing it a little too hard. When I’ve been able to make good progress, slight soreness is common (and I will say – it’s more uncomfortable than the soreness from working out other muscles, because it has more of a “stinging”/”throbbing” element to it). But usually any time I’ve been more sore than that was a result of pushing my body too much (e.g., medical exam, trying to have sex when I wasn’t ready). Dilation should be pretty gentle and slow, while still uncomfortable in the moment. If you’re seeing a medical professional or PT it might be helpful to discuss with them how sore you’re getting or how much you should be “pushing” with the dilators. Congrats on your progress!