I may very well be attacking on the first lap... or shortly thereafter.
That tucking in and pacing thing works if you can out-sprint the other guys, but my best results come from being aggressive.
Sara, my mental approach is to think of "easing smoothly into the pack". I have plenty of adrenaline pumping, and I try to be controlled and to smoothly slot in near the front. Which is actually pretty much what Esteban said. But then we need to evaluate, and decide when to attack.