It's hard to say how a Human/Klingon hybrid will mature. It could be that the hybrids of any
species mature and develop differently from the norm for either parents' species, and possibly different from other hybrids. For example, a hybrid with a Klingon mother might develop differently than one with a Klingon father.
Alexander was 3/4 Klingon, and 1/4 Human and was adolescent at about 8 years of age (assuming, among other things, that 1000 stardates is about one Earth calendar year). B'Elanna was 1/2 Human and 1/2 Klingon, and what little we saw of her childhood indicates that she didn't age as fast as Alexander, but that even she, at the age of 5, looked older than a typical Human 5-year-old.