So, I was thinking about joining this Pathfinder game. With monsters. Meaning, we are monsters with class levels.

A player of the group made an attempt to explain me the rules for advancing monster by class levels 'cause I'm new to pathfinder. Then, just to see if I could figure it out myself, I checked the book itself.

Now, however, I am confused. The explanation given to me by the players seems incoherent with what the book says.

My question is then; if the group starts at ECL 6, how many levels of Sorcerer would an imp, following the pathfinder rules, have?