There's lots of confusion caused by terminology. Many use the term "yearling" for a deer born in the spring of the same year rather than the preceeding spring. A fawn is a deer born in the spring of the same year.
Fawns are between 4 and 8 months old during their first hunting season. Their age depends upon when the season came in and when they were born. Fawns can be born in several months of the year, so there's quite a bit of variability in the size/age of fawns that are shot. I've seen a fawn with faint spots and a good-sized buck fawn during the same day in the woods. The buck fawn was almost twice the size of the small fawn.