Eddie Mathews is the 3rd youngest player in MLB history to hit his 100th HR at 22 years 292 days old. Jones is 5th, he hit his 100th at 23 years 62 days old.
Acuna turns 21 on Dec. 18th, he has 26 Hrs in a partial season. His rate of a Hr every 15.5 at bats would give him about 38 over a full season.
If he doesn't hit another HR this season and gets 38 over each of the next 2 seasons he'd have 101 at no older than 22 years 290 days old. That would put him as the 3rd youngest in history to 100 and would give The Braves 3 of the top 5 all time.
Andruw was the youngest in NL history to 300 Hrs, that is almost impossible to beat.
An interesting bit I noticed while checking these stats. Hank Aaron hit his 700th HR at 9 days older than Ruth hit his 700th, he did so 8 days further into his 21st season than Ruth hit his.