First, it is usual for a tire to stretch - especially in the first 24 hours. So setting the pressure 2 or 3 psi high for new tires will likely result in the correct pressure in a few days.
3 psi high isn't that big of a deal. I like a quicker turn in, so that's what I set my pressures to.
Don't forget that operating the tires generates heat, so measuring the pressures after operating the tires isn't what they were set at.
Plus, ambient temperature affects pressure - about 2% for every 10 degrees F.
