I carried with one in the chamber from the beginning. Having a loaded gun that is not ready to operate introduces you to unnecessary hazards without giving you any benefit from carrying.
I introduced my father to carrying about a year after I started. For the first couple months he had his permit, he actually carried his gun in the manner he normally would (DA/SA decocked w/ no safety) but without any ammunition on him until he was comfortable enough that he knew it wasn't going to "go off".
Its certainly worth getting used to operating your CCW, as well as holstering and unholstering the weapon, until you are very competent with its operation and it feels natural. However, carrying with a loaded magazine without a chambered round serves you next to no purpose.