@folks19, @Subexistence achieved a couple of 800 scores by his 20th birthday. Based on memory, he acquired about a half a dozen cards and a share secure loan during his first year of building, then he spent the entire second year gardening.
Things have changed somewhat since then. Banks are more sensitive to new accounts these days. Credit newbies need to move somewhat more slowly in order to get quality cards and avoid junky ones.
My son hit 801 within 15 months of his 18th birthday. He's an AU on some of our high-limit accounts and by the time of that score, he had 2 cards of his own with baby limits. He added a third card (with a limit of $3,000) and just had a student loan report, so now his score is more like 775.