Did they get that far in the show already? I still haven't gotten around to season 2, lol. :D

Yep. Season 4 came out in December, I believe, and each season follows one book.

I thought season 1 & 2 was book one....although like I said I haven't watched season 2 yet so I don't know where they ended it.

I'm honestly not sure myself, so I'm looking at The Expanse wiki now, so I don't give out wrong info, lol.

It says that S1 is based on most of the first book, S2 is based on the remainder Leviathan Wakes and part of Caliban's War, S3 is the rest of Caliban's War and Abaddon's Gate, and S4 is based on Cibola Burn.

https://expanse.fandom.com/wiki/The_Expanse_(TV)

Fair enough.

So, yes, you should read Cibola Burn. :)