Is my Cal Common Lager fermenting?

Last week I started a Cal Common Lager using White Labs' SF Lager Yeast, my first non-ale. I was afraid I may have killed the yeast by not refrigerating it for a few days, but after about a day and a half it seemed to have a decent layer of krausen on top and passed a few bubbles through the airlock. So I moved it to my basement where it's been hovering around 53 degrees. It hasn't produced any bubbling since the first three or so bubbles that it kicked out on the first day. All my previous beers have bubbled like mad for about a day once they got going, so I'm concerned that I might be making non-alcoholic Anchor Steam here.
Any tips on how to ensure proper fermentation? (agitate? let it warm up a bit?)
And, for the inevitable "wait it out" advice that's coming, how long do you recommend leaving it in the primary? (I haven't been measuring gravity)

I'd either leave it a week or two, or if I was worried about it not starting, I'd measure the SG. There is no way to no otherwise if it's fermenting. It could even be done by now, but without checking the SG, I'd only be guessing if I tried to answer the question.

If this is useful to anyone...
I had my primary on a cold cement slab (good for keeping even temp, I was told), but I think the yeasty bottom of the beer probably stayed a few degrees colder than the mid-section where the thermometer tape was. I moved it off the cement slab and agitated it gently (without opening), and it immediately began to bubble steadily.
Lesson learned: When a yeast says it ferments down to 50 degrees, don't push it.
Question: Will a week-long hiatus from fermentation do any damage to your beer?

No, it should start back up again and be fine.