I agree that there’s reason for optimism for NYC.

@Derek Miller 5 to 7 days prior to the date you would like your first warm body is optimal.

Price of the property, rental income, cost of permits, material, and labor for the ADU, and ARV of the property upon completion. 

The property is next to a major road and it's a corner lot, so street parking is possible but not optimal.

A landlord may be able to argue that, even if the property is fully depreciated, labor costs can be withheld.

There are prices increases in materials and a shortage of labor, so many builders have decided if they have limited resources and can sell more expensive homes, they'll shift price range focus.  

For your postcards, the intention is NOT to convince people to sell their house to you.a 4 x 6 inch postcard doesn't have the size (nor credibility) needed to convince anyone to sell their house below market value.The ONLY purpose of the mailer is to direct traffic to a fully optimized credible website.

Given the downward pressure that social distancing regulations, shortages of labor, supply chain issues, and now cold weather continue to exert on new construction, it will be difficult to satisfy demand in the short run.

The best way to find them is to send out mailers.Some good lists to target are Absentee Owners with Equity, Seniors with Long-time Ownership and Homeowners with Low Financial Stability Scores.You can work with a list broker to optimize your list for your area.

Qty 1 Home Depot part number key-55uEtc.The template had everything that might be needed in a rehab.In this manner, an investor knows the cost of material and can better judge cost of labor.