Well, if you're like me, you just hope that the vehicle polishes up to where there's a shine on the car!

My gf has a 1999 white Toyota Corolla, and the only way that I could tell that the polish was breaking down correctly on the car was that the car was going from "oxidized" to "shiny", and that was with using ColorX on a PC 7424 & polishing pad.
Best I can tell you is, work at it, change your angle often to see if you can see the polish breaking down and getting the scratches/swirls out, or else just live with the light swirls that are going to be hard to see, except at the right angle, at night, etc...