First to the notary for the purpose of purchasing land and then the building committee?

Clear answer: wait! If you then can't build your dream house because the planning committee rejects it, you'll look stupid. Notary and financing probably mean the registration of the land charge, which can be done simultaneously?! If you can build your house in compliance with the development plan with a higher budget, you should definitely wait. In our new development areas, there is usually zero tolerance!