That's very broad since it depends on what type of product you want to build (single family, multifamily, and in what markets/cities and at what scale (one or two units at a time, or larger), etc. 

Waiting to start the DADU until you’re ready to sell the main house keeps the listing clean and guest feedback positive.If you decide to hold the property for tax advantages and short-term rental income, you can start hosting now, build up good reviews for a few months, and then pause the listing during construction.

Aim to break even (or close), and look for value-add opportunities to build equity immediately and over time.

I’d suggest adding one thing: start building relationships with small local lenders and mortgage brokers now.

So one year is often not enough time to build up enough equity (from appreciation) to refinance into a conventional loan. 

I recently started thinking about investing in a multi family home and ran into an apartment building.

It's fantastic that you and your husband can GC a build. 

I bought SFH in West seattle where I am flipping the SFH and also building a DADU in the backyard.

they're just a way to use your payment for housing (since we all have one starting out) to build equity.  

I'm also building a house with Delta.