He’s made it pretty clear that he can abandon his current body without needing to wait for it to die, but it’s not clear whether he’s able to temporarily leave and return. It might be that leaving the body would mean simply letting it die. Whether he can or not, that’s probably not what he’s doing whenever he’s in “off” mode, because he’s been doing that since before Harry revealed to him the identity of the Resurrection Stone.
He’s made it pretty clear that he can abandon his current body without needing to wait for it to die, but it’s not clear whether he’s able to temporarily leave and return. It might be that leaving the body would mean simply letting it die. Whether he can or not, that’s probably not what he’s doing whenever he’s in “off” mode, because he’s been doing that since before Harry revealed to him the identity of the Resurrection Stone.