7 days is the fastest I've gotten roots in the aero cloner.
The bigger ones do root first usually but I attribute that more to the amount of exposed cambium at the cutting site(the thicker the stem the thicker the cambium layer is). If you give it a very hard angle when you cut then you have more surface area for the cambium to begin rooting. There is a delicate balance between cutting the cambium off and exposing a thin layer but still the harder the angel the better. A friend told me he likes to scrape the sides of the cutting to get rid of the epidermis and allow a closer access of the cambium as well. I have also noticed that the smaller cuttings will end up rooting through the epidermis due to the fact that it has a thinner epidermis than a bigger cutting.
The key is to be very observant and experiment.
