We use the lender's calculations for your qualifying income as our figure, so you'd want to talk to your loan officer about how they calculate.  If you don't already have one, consider using a CalHFA Preferred Loan Officer.  They have expertise in the challenges that first-time homebuyers face. Here's a link to our list, searchable by county:

https://welcomehome.calhfa.ca.gov/directory

Loan officers can work in any county, so don't limit yourself to one or two.