I made my CPH 1" longer. And of course, you're right: the time to do it is before you begin your armhole decreases.
But there have been many sweaters that I make longer! Some have been 5" longer! Especially, Mmy KHAKI CABLES white cotton cardigan: it is shown in the book as a cropped cardigan. I made mine to ride over my hips. Prolly 5" longer.
And the answer given about the 14" is right. When a pattern says something like "when the pieces measures 14", begin the armhole shaping"...unless stated otherwise, it always means the whole shebang.
OK, I'm off to work on my brother's jacket!