We encourage you to take your impressions and return them to us by the return date, so you can get your smile on the road (so to speak). :-)

The sooner you get your kit back to us, the sooner we can continue the evaluation process. 

However, the putty won't 'go bad' if you take a few weeks longer. As long as you don't keep it in a very hot environment, where it can dry out, your kit will be fine. 

BUT - once you make your impressions you need to return it to us right away - especially if you've had braces or retainers in the past. If you wait too long, your teeth may start or continue to shift - not good for making accurate aligner models.