Pushing something off to an arbitrary block of time in the future does not equate to being productive. In fact, it's quite counterproductive.
Rather than pushing a project into a black hole of a calendar, be more finite with your expectations.
"I'll do it Wednesday after lunch" sounds like a much more satisfying response for a manager to hear.
Not only that, but now you'll hold yourself accountable to get the project done.
Be more specific with your time management and your tasklist will thank you in the long-run.