So my first idea is: If I can only increase my age once from character creation to the end of the campaign, is there any event that makes it more convenient to do it later than character creation?
And my own answer is yes, if you would start with an even score, and I should consider an odd score anyway for checking when to buy tomes, because the age increase should come with the first tome, since a +2 tome costs more than a +1 one and +1+1 would therefore let me carry more money to the next level, possibly letting me purchase other tomes earlier.