Sometimes never....
First you don't even concern yourself about
fermentation beginning for 72 hours because;
Fermentation can take 72 hours to start.
But more importantly, airlock bubbling, lack of airlock bubbling, stopped airlock bubbling, fast airlock bubbling, slow airlcok bubbling, heavy metal airlcok bubbling, or disco airlock bubbling
really is not an indicator of what is happening to your beer. It is NOT a fermentation gauge, it is a valve to release excess pressure, excess CO2...NOT AN ACCURATE INSTRUMENT....
I have 9 different fermenters and have been brewing for a few years, and OVER HALF OF MY BEERS NEVER HAVE ANY BUBBLING IN THE AIRLOCK AND THEY ALL TURN OUT FINE!
Fermentation is not always "dynamic," just because you don't SEE anything happenning, doesn't mean that anything's wrong, and also doesn't mean that the yeast are still not working dilligantly away, doing what they've been doing for over 4,000 years....
Right now your yeast is cominng out of a dormant period, it finds it self surrounded by 5 gallons of food, so it is waking up, and waking up its friends...THEN before it starts truly diving in the yeast start growing an army to best eat it, so they have a wild orgy and then make a bunch of yeast babies.
Then they get to work. SO that can take up to three days before the really get going..it's called lag time, and it is perfectly normal.
If you've oxygentated, and pitched plenty of yeast, then you SHOULD reach your yeast attenuation, and get close to the final gravity.....that is all that is important...NOT whether or not you airlock goes "blip" or "Rattattattatta!!!!"
An airlock is a vent for excess co2, nothing more, it's to keep your beer off the ceiling, and is designed to vent and still keep stuff out of your beer....that's really it...
In fact many no longer use airlocks at all, just cover the hole with a piece of tinfoil, or use a piece of plexiglass instead of a lid.
Read this for why airlock analysing is useless, and what is the only gauge of ferementation...
https://www.homebrewtalk.com/1217925-post3.html
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.....
So ignore your airlock, ok???? It's fun entertainment to watch, but doesn't mean anythings wrong if you don't see it.
Welcome by the way...Just relax, the yeast knows what it needs to do and will do it when it's ready.
