Fermentation time for any beer is not set in stone, a beer is finished when the GRAVITY is stable for 3 consequtive days. An airlock is a valve, a vent to release excess Co2 and keep beer off the ceiling. It is not a magic fermentation gauge. It only bubbles when it needs to release co2, but that doesn't mean that if it isn't bubbling fermentation is finished, the yeast are still often working, but not producing a ton of EXCESS co2.
The most important tool you can use is a hydrometer. It's the only way you will truly know when your beer is ready...airlock bubbles and other things are faulty.
The only way to truly know what is going on in your fermenter is with your hydrometer.
Like I said here in my blog, which I encourage you to read, Think evaluation before action
you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right diagnostic tools
before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in....
Thinking about "doing anything" without taking a hydrometer reading is tantamount to the doctor deciding to cut you open without running any diagnostic tests....Taking one look at you and saying, "Yeah I'm going in." You would really want the doctor to use all means to properly diagnose what's going on?
I recommend that new brewers wait a minimum of 10 days before even considering taking their first grav reading. If I take a grav reading I usually just wait til the 14th day.