Adu/ garage apartment construction.

We have a small west university house but want to build on the detached garage. About 350 sq ft of mother in law suite. Preferably with a full bath and kitchenette. It’s concrete slab foundation on wood studs. With electric and water but no sewage. I don’t plan to get it done till later this year but can someone share if it is possible (with city permits etc) the timeline and cost ballpark involved. I’d get the contractor but plan to do so in 6 months or so. Thanks !