A. Yes. Force yourself to get started. Make at least incremental progress, even if you only invest one hour. That way, the next time he checks in, you can report some progress. Beware: Whenever a boss asks you to do something, resorting to the “I’m too busy” excuse is a career-killer. It’s better to ask, “When do you need that?” and make time to chip away at it.
If you think your other work will suffer badly, ask your boss how you should prioritize your duties. He may not care about something you regard as important.