Quick lager primary fermentation

[masaba]

I brewed my first lager last Friday. Chilled the wort to ~55 degrees, and pitched a decanted 1 gal starter. The OG was 1.052. The lager has since been sitting steady at 52 degrees, right in the middle of the recommended range.

I had read that primary fermentation takes around 7 days, but it seems that yeast activity on my fermenter really started slowing last night (4 days). Is it possible that my lager is ready for the D-rest so soon? I have heard that if I let the primary go too long, then I miss the chance for a D-rest, so I don't want that.

Edit: Looks like I may just be nervous. I am using a plastic ale pail, so I can't see the activity, but I am still definitely getting activity on the air-lock. It is slower than it was a day ago, but it looks like the yeast is definitely still working rather hard.

 

[wobdee]

The best way to know for sure is to take a gravity reading and see if your fermentation is 75% complete then it's a good time to raise temps for a d-rest. I use to do this but found is was around 75% after the krausen falls and the yeast cake starts to develops so now I just wait for that. This usually takes 6 days for my 3 gallon lager batches at 50 degrees.