Over on the Human Resources Executive Search blog, there is a great post about how to assimilate successfully into a new company and job. When you join a new organization, it's important to observe before you act, immerse yourself in the company's culture, and cultivate relationships with people who can serve as mentors. It's generally recommended that you avoid making significant changes when you first arrive or saying things like "When I was at company XYZ, we did it this way"

The first 90 days in a new job provides an opportunity for you to solidify the relationship that you created during the interview process, build credibility and trust, and prove that you fit into the company and culture.