I'm ripping off the fairy tale "Lucky Luck", in which we are told
When the lad was about eighteen years old his father had to go to fight in a war against a neighbouring country, and the king led his troops in person. He bade his son act as Regent in his absence, but ordered him on no account to marry till his return.
Time went by. The prince ruled the country and never even thought of marrying. But when he reached his twenty-fifth birthday he began to think that it might be rather nice to have a wife, and he thought so much that at last he got quite eager about it. He remembered, however, what his father had said, and waited some time longer, till at last it was ten years since the king went out to war.
and I considered that and said, "No way." The prince perching so cheerfully in the outline is not going to be 28 when the significant events are triggered, but rather younger. A youth rather than a man. But the years of waiting matter. He's not going to flout his father's command within weeks of getting it.
Was thinking of ripping off the common medieval age of majority of fourteen. At which point my king, more eager to fight than the one given, would be able to make him regent. (They did the opposite for Louis XIV, declaring him of age (at thirteen, actually), so the unpopular regent/queen-mother could slip into the background.)
And then how far can I trim the years? A nice, round seven years would make him twenty-one, but I don't know if that's older than I like. Eighteen might be better.
It would also have the advantage of there being less of a gap, because the story starts when he is seven -- and I can't move that much forward because the fairy tale I'm ripping off there calls for some folly and some timidity both of which are more likely for a young boy. Especially given they are not consistent with his later character. . . so there's going to be a large gap to finesse. What fun.