Link to P-Slings PSNY Wearing and Care Instructions:
http://www.pslingnewyork.com/instructions.html
Hotslings Sizing Instructions
Courtesy of Hotslings (tm)
Click for Hotslings Sizing Calculator
Correct sizing for pouch slings is essential for the happiness of both mom/dad and baby. Find your best fit with our Size Calculator (use pre-weight, if you get more than one size recommended and have big breasts, broad shoulders, a big 'ole baby, or wear bulky clothes, pick the larger size.) Most people wear a 3, 4 or 5.To measure from shoulder to hip: use a soft tape measure and start at the outer corner of your shoulder and measure diagonally across your body down to your hip bone. The number (in inches) should be in the 20s.


Notes on fit: Everyone is different. What they can and can't tolerate is largely preferential. Some people can wear more than one size and that's OK. It's like going to the clothing store and being able to buy jeans in both a size 6 and a size 8. They both fit, maybe one's slightly looser.
Too Small: feels uncomfortably tight, digs into baby's legs, it's crazy hard to get baby in.
Too Big: baby feels insecure, your legs bump the baby as you walk, your back aches after a short time, sling slips off your shoulder.