Measure from start or from patt?

I’m making the Bernat Camouflage Child’s Cardigan and I’m questioning where to measure from for the instruction in bold below

With smaller needles, cast on 75 sts. Work 2 ins in (K1. P1) ribbing. Change to larger needles and [B]proceed in stocking st for 15 ins[/B], ending with a purl row.

Is it really saying to measure the 15 inches just for the stockinette part? I’m so used to measuring from the beginning of work for stuff, that I need to be sure here. Will it be 17 in total (with the ribbing), or 15 total?

I would think it means to knit 15 ins. in stockinette. I think it would have said “from beginning” if it meant the ribbing also.

That’s the way I read it. I believe it meant from the beginning it would say “from cast on edge”.