They tend to be easier to pop when they are younger and more "squishy". However if you don't know what you are doing, I would urge to find someone who does, if you do it wrong you could severely injure the animal. I've been keeping snakes for 10 years, and still don't fully trust myself.
Where in your dwelling are you keeping the new snake? It may be in its own container but, if its still within close proximity of the others, that kind of voids out the quarantine process. Make sure its at least in a separate room.