Far from it. Now is always the time for relationship-building: between you and the company’s executives; between your direct reports and the middle managers; and between IT and business staff. Without effective relationships, processes fail and influence is nonexistent.
Let everyone know your plan. If you're new, you have a grace period, but must show tangible progress before it ends. If you aren't new, you need to make a persuasive case explaining why you're still in a position to lead effective change.
Master management before leadership
If people are following, then you're leading. Otherwise, you aren't. That's what leadership is about: setting direction, and getting others to head in that direction without your having to drag them along. Management, by contrast, is about getting things done -- about defining good processes and producing quality results efficiently.
Leadership is, if you like, about strategy; management is about competence.
If you accept this segregation of responsibilities, then make sure you master management before you master leadership. As a practical matter, there's a limit to how wrong the things are that you're likely to do, but no limit to how badly you might do them.
In business circles, the importance of being a leader has received a lot of attention over the past couple of decades, while "manager" has become something of an epithet. That's unfair. From a hard-nosed business perspective, results pay the bills. Leadership is just one technique among many for making sure results happen.