[ellen]

Is it no burps in the airlock at all?  How long do I have to stare at it?  I have not checked the gravity yet but I plan to do so.

[Hokerer]

Burps in the airlock is a completely unreliable indicator of fermentation.  It's common to have a gasket or something that's not completely sealed and the gas escapes that way bypassing the airlock.  That doesn't cause any problems but your airlock won't burp.

Take a peek in the fermenter and see if any krausen has started to form on top of the wort.  That'll tell you something.  If you're wondering about fermentation kicking off, it's probably too early for a gravity reading.

[thcipriani]

Well, that depends - are you at the beginning or end of fermentation?

No CO2 coming out of solution is definitely a sign that there is no fermentation occurring, but it's far from definitive.

If you're at the end check your gravity one day and then two days later - if it's the same then you have no signs of fermentation.
If you're at the beginning of fermentation check the pH of whatever you're fermenting - it should be lower than when you pitched - that's a sign that fermentation is getting ready to start.

[ellen]

Ahh, I should have said that one burnt mead is 10 days old and is burping about 23 seconds apart--was every 10-12 last time I checked. 
I have a cyser still in primary after 5 weeks--burped 3 minutes apart. 
And a melomel in secondary about 10 weeks old--no action at all I think.
These are my first three meads.
Ellen

[ellen]

I should have also mentioned that the cyser and melomel both fermented well--at least I saw lots of steady burps (too many to bother timing) and then they both gradually slowed down.

[morticaixavier]

I think you have to go by gravity readings. as was said above, if at the begining of fermentation it's more tricky but there is also the color aspect. When the yeast has fully colinized the must it will look milky. (are you fermenting in glass or buckets?) If it has fermented well and you are just wondering if it is done use gravity readings.