Listen to Lampwick guys, he is speaking some wise words... but if you absolutely have to, put on the rubber band while you edge and take it off after around a half an hour or so. This is what I started with when beginning my quest for girth. Keep your cock warm while you are edging... this will keep the rubber bands warm as well, which will improve the elasticity of the rubber and save your delicate capillaries from getting fried. I suggest edging with a rubber band under a pair of sweatpants, this will keep the heat goin'. Take the rubber band off and apply a normal cock ring or leather strap when you are done. This will hold your girth gain for hours.
I have been using a leather strap for years and have been in some tight places where a chick has literally knelt down under a street light to give me head while I had the strap on... YIKES! I quickly said, "Let's move to your car where there is more privacy." She was like," Oh, alright." and got up and unlocked the car. While I was rounding the vehicle, I slid my hand down my pants and quickly unsnapped the strap and pulled it out before I even put my hand on the door handle. She sucked my cock straight for like 20 minuted... I had three orgasms during this time... she swallowed every drop! She was also a no-hands expert and literally feasted on me!