I keep my cuttings at around 73 F. Most of the varieties this I am rooting this year seem to take 20-24 days to reach a point where they can be cupped, with a few rooting as fast as 9 days and others rooting at 6 weeks. With very few exceptions, once roots actually begin to form, they are ready to be cupped in just 2-4 days. If I wait longer, I have a mess detaching them from the paper towel.
C.J.