Slight at 7 weeks will likely be severe as an adult. The beak grows constantly- and if not aligned properly- the problem will perpetuate itself and get worse.
search for scissor beak, lots of discussion on it. trauma or genetic cause. no easy fix, and unlikely the bird will ever be normal. most do not get appropriate care and monitoring and do not get enough to eat, are stunted and end up sadly starving to death around 6-12months as the problem gets more and more severe.
you can try to correct it, but if you cannot commit to weekly checks on crop and weight, as well as probably weekly to every two weeks beak checks and dremmeling- culling would be the kind thing to do in most cases.
The chick may not be in any pain right now, but it will likely become perpetually hungry. In many cases, the lower beak dislocates as the top beak curves around and pushes it to the side. This is painful.
The rubber band might help realign the lower portion, if the upper beak is dremmeled to a normal shape. But as the underlying problem is still there (trauma or genetic issue with growing part of beak), it will likely continue to grow crooked.