Ooh I just emailed you but I'll post here as well - I'd say at least an hour minimum, 2 hours is much better. For maximum awesome though, at least 6 hours would be best. I've written about the health benefits of soaking nuts/seeds here, if you're interested.
But just for creaminess, at least an hour or two is all you need.
Thank you for both replies, Sayward. Right after I started this thread, I noticed that the one with your recipe got bumped -- until then, I'd forgotten where I'd seen it -- so I went ahead and pm'd you because I was desperate to make this dessert! In case anyone is wondering, it's in "ideas for vegan desserts that taste good".
The torte is in the freezer, and I can tell it's gonna be.