* Stop when you have a big winning, by channeling the money somewhere else so you won't lose it back to gambling.
I do not know what you mean by big winning because most gamblers can not win up to that. But it is good to stop even if it is small winning already. Continuing gambling will only later likely lead to losses.
* Stop when you are not even winning at all, it's not your thing.
I do not think this is possible. If you do not have fun while gambling without thinking of the money to win, then it is not your thing. If you gamble with small amount of money many times, you will win and also lose. But if you win more than losing in some few gambling time, then it is good to stop.
You are actually right but I don't think it's possible to stop when a gambler is winning than lose, he will want to gamble more and gets more win.
And this is what can possibly lead to addiction if not properly not handle by strict rules and the more he will gamble, he might lose all the money he wins in the process. So it's very wise to gamble responsibly for the sake of our mental health and so on.