These updates modernized the property, improved its curb appeal and significantly increased its market value.

Total PITI : $2,800 p/m ADU: Rents : $1900 p/m Home : would rent for $3k per month Potential Gross cash flow: $2,100 per month Purchase: $500k Current ARV: $900k Can these numbers be achieved today with high interest rates and high prices ? 

Can I rent it after the fact?

I am renting out my first property and I have a tenant that is interested in the property but wont be able to move until August 2024.

I keep a running excel sheet going of market rents in my area as well.

I would also try to raise the rents of other units before the sale will help you sell it at the highest price.

If the property is 3000 square feet and your rented a unit that is 1000 square feet, you are basically renting 1/3 and depreciating $100,000.

The rent is not realistic with the bed/bath count and the condition;it needs a large rehab.  

That could be a good solution if the properties are good and rents are good to not lose the cash flow.

The best advice I can give you is to rent for a year.