Congrats on your first boa! I'm sure it won't be your last. I have three, a BCA male, a Central American motley male, and a BCI hypo male. All three are great eaters, curious and calm snakes, and a joy to handle.
Yours looks like a common boa (BCI) in one pic I was thinking maybe anery, but the other pics show warmer brown hues, so I'm thinking you just have a very nice looking normal.
The specking / freckling is a trait of most boas and it varies in amount... my hypo BCI male is quite "dirty" too and has a lot of freckles, but I think it adds character.
I'd agree that yours looks to be ~18 months - 2 years maybe.
I highly suggest using hook / tap training to help your boa learn when it is and is not feeding time. These guys have a crazy high food drive and I have often had to use the hook to bring mine out of food mode (My BCA will slam the glass at any sign of motion when he's hungry).
I would also suggest doing a lot of research into proper feeding schedule. These guys need to be fed a lot more carefully than BPs, as they will get obese quickly resulting in fast growth and a shorter life span. For a boa the age of yours, feeding every ~2 weeks would probably be fine. Most people keep theirs on mice until the boa is large enough to take a small rat and then switch.