Roast times vary a lot from popper to popper. Even two units of the same make and model can exhibit very different roast times. The ambient temperature and the line voltage can influence things. If you get to second crack anywhere between six and eighteen minutes, you will be able to get great roasts.
I recommend doing a few experiments to see if there is a general profile that appeals to your palate. It seems like people are divided as to whether thay prefer a longer ramp from start to first crack or from first to second crack. Try it yourself. Take a look at your log and see what your first crack time is. Use the various techniques described above to move the first crack later without doing anything to influence the first crack to second crack stage. Do some roasts where you leave first crack where it is while extending the time between first and second crack.
My personal preference for my Toastmaster (with just under 1/2 cup of beans which is about 72 grams) isto get to first crack at about 4 to 5 minutes and get to second crack somewhere between 7 and 8 minutes. The times can very as much as a minute in either direction depending on the bean etc.
On my Wearever Pumper, I tend to roast more beans (from 100 to 130 grams) and get great results with first crack around 4 or 4 1/2 minutes and second crack anywhere from 9 to 14 minutes.