Once he’s summoned and then unsummoned, you can bring him back right away. There’s no cooldown. You can also steal him from one summoning to a second summoning. So if he’s captured in a sigil, and a worshipper summons him again via a different means, the god will break his containment and move to the new vessel. This… this is very important to know. I learned it the hard way. The hardest way possible.