I'm assuming you're going to have 1/2" cbu and tile on the wall? Mock up all of the parts and decide where you like the looks of it. Based on the manufacturer's guidelines, if the trim fits, it's okay. That doesn't mean you'll like the way it looks if you're at one end or the other of the allowable placement. BTW, this isn't a Delta unique issue...most companies are a little confusing - the min/max are likely correct, but the best asthetic placement may be somewhere in between.