Thread was closed, so I'll tell you.
The highest IV is always listed by characteristic. If it's a 31, 26, 21, etc., you can tell the highest IV. To check once I see the right characteristic, I put it in Day Care, ride around until level 10, then get a more accurate idea from Serebii, then reset if it's not what I want.
Or at least, that's how I used to do things.