Wanjy has an approved plan... which means an engineer was involved to do the structural design.
Equipped with the drawings, is raring to go.
Go for a labour based contract where you provide all the materials and the foreman (senior fundi) provides labour. It works well if you can schedule the work when you or someone close to you is available, otherwise you'll be fleeced dry.
Phase your project... (is it a bungalow or a Maisonette?)
Foundation => Walling => Roofing =>Metals(Windows & External doors)=> etc
"..I am because we are. "― Ubuntu, Umtu,