Hi James,
The earliest you can weigh-out for the challenge is 2 weeks prior to your end date, even if you have met your goal early. We want to encourage weight loss and weight management over time. Our goal is to help you get the weight off and keep it off, develop new habits, and a new lifestyle over the course of your challenge. If you meet your goal early, you'll just need to maintain or continue losing (as appropriate) until that weigh-out window opens.