Single family usually is done in anywhere from 4-6 months once you break ground, with a few months of design/permitting prior to that. 

1- It's important to have a good relationship and communication with your contractor.2- While it may take more time up front, planning as much out in advance as possible in terms of design would have saved several headaches.

In the process of designing another 19 units to add to the mix.

We’re in the process of designing the house with an architect.

If you do not want a developer to have design control and do whatever makes them the most money instead of what the town needs to be revitalized you should put in the NDA that you (or a group that you control) have design control over the project and that you will reach out to an architect with this type of design experience for professional work.

Take a look at my profile, I am in the midst of designing a UDemy style course to help with getting started.  

@Marcus Auerbach - Most urban and suburban cities/towns require someone to assume responsibility and also take liability for areas of design and construction which affect public life, welfare and safety.    

But if you are going to take this as a step in a direction that you think you want to make a career out of designing functional spaces  and know how to make structural decisions and how that effects design, then I would suggest looking into architecture as a career.

A lot of the time the design firms have a couple of designs that they have had success with and recycling them.

The legislature shallprovide for the determination of true cash value of such property; the proportion of truecash value at which such property shall be uniformly assessed, which shall not, afterJanuary 1, 1966 exceed 50 percent; and for a system of equalization of designated realand tangible personal property in lieu of general ad valorem taxation.