Would that be when they are self sufficient? If so not mine.
It would usually mean that at that point guaranteed cash value is increasing on an annual basis by an amount equal to or grater than base policy premium.
As for the policy being self-sufficient, it sounds like you're referring to the stage where annual dividends equal or exceed the annual premium. Practically one can usually offset the premium at an earlier stage, by using not only current dividends, but also surrendering previously credited paid-up-additions purchased by dividends (or using the policies option to purchase paid up additions). Doing that will result in the death benefit (which has increased due to paid-up-additions) to be reduced for several years, until current dividends catch up. But even with that cash value would be increasing.