Sorry you lost your old guy. Sounds as if your hens were mourning too, they don't always, but can do that. Is the new guy new on your property? If so, 1 month for bio-security reasons, don't wanna bring in a roo, only to have him bring some unknown disease into your healthy flock. He'll need at least a week or two of "Look, don't touch" time with your existing flock near the end of his quarantine. If he's lived on your property for some time now, has he also had some "look, don't touch" time with your girls of at least a week, or two? If so, you can probably integrate him now... If not, that would be your next move.