It depends on the parish and the diocese. Do all of these girls go to the same church? If so, you could simply call the church and ask them. Most of the parishes around us have Confirmation towards the end of 8th grade. So they don't even offer classes after 8th grade. I used to work at a nearby church that was a real rebel and had Confirmation in December of 11th grade (and had to listen to parent complaints every year!).
If you can,I would call the church and introduce yourself. Ask them if they would give you a calendar and any other information. I would have done that for you when I worked at the church.