8 months is really nothing when you think about how long puberty takes in cis males. They generally start puberty around 12/13 and most can't grow anything worth keeping until their early 20's or later. Even after the main part of puberty is over your body continues to grow and change and your facial hair will continue to change and improve in growing ability. So yeah, try not to be too disappointed, just remember it's not a race, and that genetics play a role in how well and how fast your facial hair will grow.
If the guy you are talking about is loadingoliver, it's not all minoxidil, he's been on T for 3 and a half years, so there's that. Then there's the fact that you don't really know how much of the hair growth these guys get is actually from the minoxidil and how much is what was going to grow anyway (meaning minoxidil didn't really make a difference, but they thought it did because they were using it).