Lag Time When Pitching on a Yeast Cake?

What's the average time everyone has experienced from pitching onto a yeast cake until active fermentation? I pitched my 999 barleywine onto a Nottingham yeast cake yesterday and now over 12 hrs. later it is still just sitting there. After everything I heard about people having fermentation within a couple hours when pitching onto a yeast cake I'm a bit surprised. The beer the yeast cake is from is a 1.040 OG stout, primary fermented for 5 weeks. Is it possible, since the yeast hasn't really fermented anything in about a month that it's "asleep" or has been shocked by being showered in extremely high gravity wort?

I believe the yeast were just shocked. Give them some time and they will start. I had the same problem with my 999 BW

A quick lag time isn't always the greatest thing. Yeast still need to go through reproduction (which is what may be going on with your batch) before they begin their fermentation.

It'll turn out fine, I'm sure.