Came down today and the ich has fallen off Groucho "the oscar" so it's now in the stage where it can be killed.
Well, what you saw fall off were mature parasitic trophonts. You likely have immature trophonts attached to any number of fish that aren't affected by the salt yet. Also, any number may be hidden on the gills.
I would give it at least 10 days from when you started the treatment, although 14 is my preferred choice.
86 alone will not kill every strain of ich. If you're only using heat, I'd recommend 89-90, but as you are using salt, the 86 works fine.