Does anyone know exactly how much time passed between Kagome getting pulled down the well until the well seals her out for those three years? Is it months? I know it can't be years, but then I could be wrong.

The Manga/anime happened during 1 school year. It is unknown what the date was when Kagome was pulled in the well the first time. The Japanese School actually starts in April and runs through to march, but there is a vacation of a few month for summer. Since there is no indicate of that summer break, I would assume she was pulled in afterward. So probably August/September. If this is the case, then the time line would be about 8-9 months for the entire hunt

Thanks. This helps a lot.