Hi,
Sorry to disappoint you; however, talking of "Impression Management"... I couldn't agree with it.
A) It's easier to create a great impression, but it's difficult to live it all along. Do not set unrealistic expectations.
B) It's better to be assertive than to be deceptive. You may be successful with your dealings where you just want to create a great first impression (ref: MAGIC, Making A Great Impression on your Customer). However, that's for sales guys.
To be "effective," you need to be dynamic and honest and set realistic expectations during all your interactions, be it the first or the last. The point is, do you want to be successful or effective? Success is just a milestone (short-term); to be effective is an amalgamation of all actions included and its impact on people's perception about you (long-term). So you have a choice...
I hope this helps! Let me know if you have any questions.