It all depends on how warm the soil was when you planted, how deep you planted & your weather. Also some dahlias take longer to wake up than others. You can do a little poking around & see if there's anything growing under there but be careful you don't break off any starts. Walt (aka- the husband) usually gives them a couple of weeks & if nothing shows he'll carefully dig them up & have a look- if there's shoots replant quickly & pretend you didn't really disturb them!
If when you plant you just cover the tuber with soil it's easier for the shoot to get through the soil- then you fill in the hole as it grows.

Thanks for the advice Plantlady. I'm in coastal San Diego so we use the method of digging a deep hole, covering with a couple inches of soil, adding more soil whenever the plant growth hits a couple of inches, etc. (Not sure if that's how everyone else does it.) The weather has been much cooler than normal lately but the sun is still pretty strong so the soil warms up OK.

I guess I'll give them a few weeks before I start digging. Another one came up today but I still haven't seen anything from the tubers that had no eyes. Guess I just need some patience.