1. dragons reach adulthood at age seven, and just like some countries, they probably have different maturity standards than we do
2. moon said in book 6 that jade mountain accepted dragons of all ages
3. apparently months are based on moon cycles so since the dragon world has 3 moons, their months/ years would be 3x longer than ours.
4. it makes sense since most people become a parent around 30, which most dragons do according to my method, age 10. I will admit it gets stupid past that point though, because like nobody's gonna live to 336 years old
