Manufacturer checklists for fuel injected low wing planes that are very similar to our RV?s (Mooneys & Arrows) call for boost pump ON before start for priming then OFF. ON for Takeoff and Landing. All other times the electric boost pump is usually OFF. I like to turn the pump ON when taking the runway for Takeoff and leave it ON until about 1000? agl. Approaching to land it comes ON when I run the Before Landing Checklist or Flow or no later than entering the pattern, then OFF after landing. Boost pump?s main purpose is to back up the engine driven pump in case of failure and to provide fuel flow for starting.