Does this sound a bit too quick to you?

[OilBaron]

Brewing a lager. It took just under 3 days to see any air lock activity, and air lock activity stopped on day 6. I measured today with the hydrometer and I am at about 92% of the final gravity as per the instructions with my extract kit. Temperature was 60-64 degrees. No off smells or taste.

I sensed some diacetyl - is 67-68 degrees too warm for a diacetyl rest? I know I am a bit late to the game in terms of the hydrometer reading but I am hoping I can help it out still.

I've been reading through the forum an many people say #1 my temp is way too high and #2 it can take 2-3 weeks for air lock activity to stop.

 

[COLObrewer]

Pretty high temperature for a lager, this is probably why your ferment was quick. Diacetyl rest should be about 10 degrees higher than ferment temperature and when you are appx. 75% of terminal gravity, not sure it will help in this case but it's worth a try, you will probably need to lager for quite a while to reduce the off flavors as well.

Airlock activity only means that gas is or is not escaping, it has NOTHING to do with fermentation.