Similar issue here for me. It's been 13 hours since pitching yeast. But, a couple things that make me wonder what's taking so long...
1. We used a 1400ml yeast starter.
2. We brewed a Northern Brewer Imperial Stout extract with an OG of 1.090.
The basement is 65 F, and we're using a blow off tube and a bucket for primary. After reading reviews about this brew's fermentation, I was half expecting to wake up this morning and be able to strap the primary onto my back, point the blow off tube downward, and use it as a jet pack to fly around the neighborhood, but no sign of anything yet. Strange?