The three professions sound like a good way to give players different playstyles from the start. Are you considering a short profession-specific first objective so new players immediately understand what makes farmer, merchant, and mercenary gameplay different?
Yes! Each profession already has its own introductory quest line in the current source. The farmer starts with basic farm work, the merchant works toward a first stall sale, and the mercenary has a combat-focused introduction.
I'm still testing whether those opening tasks make the differences clear quickly enough. Ideally, players should get a feel for their profession by doing something useful, without having to read a long explanation first.