You definitely don't want to get into a situation where you can't finish the house so I wouldn't wait on this. 

Yes, it can take more than a year to build an ADU, but it's much more common -- in LA, at least -- to finish an entire ADU project in six months.

But we eventually reached the finish line and when we did, when all was said and done, somehow I made a $30,000 profit.

By the time it's finished in 2-3 years we should be through this market cycle  . . .

Wynnefield is a great neighborhood, I ended up moving to this house after we finished updating it

If, and it is a big if, we can get this structured favorably, that would leave a 2BR with finished attic (list as 3?)

Although, I want to hold out paying for everything until it is finished.  

I just did a DSCR the other month on a duplex in Detroit I just finished up.It appraised for $193,000 and each unit is rented for $1,200/mo.The DSCR is at 8.00% and PITI is something like $1,130/mo.The deals are out there, you just need to know where to look.

you want to do everything in categories . home deopt may be just lumber and finishes . all of the other trades come with their own materials 

Agree with most of the comments regarding painting the walls, putting a finish on the floor, and adding some gaming systems unless you have a loft area inside to do the Playstation / X box setup.