A cocked revolver may be an ND waiting to happen if you don't have training. A lot of human factors research has been done on gun handling under stress and a single action pull can easily occur.
Also, Mas has documented a police officer who got into trouble as he was trained to cock his gun and then shot a person by a twitch.
So the technical answer is that it is a bad idea. About clearing the house, it is difficult against an opponent by yourself. The suggestions to train and/or rearrange the house for security make a lot of sense.
Those are much more important than the issue of cocking the revolver.