You should budget to assume you can cover 6 months of operating costs, because, and if this is your first one, unless you hit a total winner with renters (you likely won't) you could end up paying both rents on the duplex (the full mortgage) + your mortgage, on a single income, and you have two kids. 

Learn deal analysis and financing so you can spot winners fast.You’re starting from strength, and if you ever need insight on funding options to pair with your skills, I’m happy to help.

in the right area those are winners..

Opportunity wait's on nobody so often what separates the watchers and the winners is the gut's to pull the trigger. 

You can get them on-line or in my market you can get them at large boat stores like West Marine.  

You need to be the guy who can find winners and has all the right framework in place. 

(The only winners in most lawsuits are the attorneys.)

So, if the worst that happened to you is the contractor was a few months late, you are a big winner. 

You anticipate that the winners provide much more profit than the losers, and you end up with a portfolio that produces a double digit return + a “salary” for your active participation over time. 

Hey Li, my good friend works for a hard money fund that specializes In OCC bridge loans up in Mainly Marin county, but the general bay area as well.