We started with Quickbooks for all of our estimates, invoicing and book keeping. I was doing book keeping my self, but when i was doing my first year taxes, my tax person offered to do bookkeeping. I agreed. Also all of our projects were residential, but as we grew, we naturally grew with the systems, and you gradually adapt. By the way, Quickbooks got really fancy recently, until now it always glitched and didn’t have much interface