Honestly in a perfect world the beer may have been ready to rack but its not a perfect world and the kit instructions usually just plain suck!
Gravity readings will tell you when the beer is done and bubbling air locks only mean gas is venting. Gas can vent from fermentation, temperature, pressure, or simply bumping the fermenter.
10-14 days is generally a good time to take a reading IMO. When you get 2 of the same readings over 3 days you know FG and then I like to give the beer another week to clear and condition a bit.
If you pitched low, fermented high or did anything that might produce off flavors than more time on the yeast will help clean some of them up so even an additional week can be beneficial as well. Many people simply leave the beer on primary for 3-4 weeks and then package