Typically 3-4 days, but doesn't taste bad after mixing it. Got to note though, I use a Dremel with a frother (at 20-30K RPM's) attached to it to mix my creations. Some say it takes away days to the steep time...
This recipe surprised me at how good it is considering how simple it is. Deserves more credit than it has got so far.
I too mixed it with a frother, and after a few days it's much better than it was as a shake and vape.