ADU development concurrent with main house

[Brian C.]

To anyone that has knowledge/dealt with ADU's being developed in these cities: Pasadena, Highland Park, Glassell Park, Alhambra, Montebello, Monterey Park.

Can I work concurrently on the main house remodel while converting a garage to an adu or does the main house need to be completed with all inspections signed off before any work can commence on the ADU conversion?

I've already asked the building department in each of these cities, but just wondering if anyone has dealt with this firsthand already.