About how many minutes of HIIT should I do to see results?

Depends. How intense? How often? What does your diet and weightlifting routine look like?

Anywhere from 2 to 25 minutes. We need more info.

on non-workout days i do 23 minutes. 5 minute warmup then for the next 14 minutes my intervals are "all out sprint" and "nice easy pace". then the last 3 minutes are a cool down.