I want to make a young-looking wood elf who appears to be 19 in human years. I've had some major problems and arguments in the past with how elves age in relative terms to human age appearance. How old would a wood elf be, if he just started to look 19 from a human perspective?
They would be 19
Although elves reach physical maturity at about the same age as humans, the elven understanding of adulthood goes beyond physical growth to encompass worldly experience. -phb
So at 19, they would look 19 in human years. They would be a litte over a hundred to be considered 19 like a human.
An elf typically claims adulthood and an adult name around the age of 100 -phb
an elf's appearance doesn't change with age after the age of 18