When do you stop referring to a baby as a newborn?

I stopped referring mine a newborn at a month .

0-3 newborn 3-11 infant 12 and up is toddler

Whenever you feel they aren't a newborn anymore lol. I stopped saying he was a newborn when he turned 1 month. Whenever someone asked I just said he's a month old, 2 months old, Etc

after 3 months I believe