Hello, unfortunately, this product is not suitable for a 7-week-old.
Very young infants can be sensitive to essential oils, so it's best to follow the manufacturer's instructions and only start using it when they're 3 months or older.
In the meantime, you may wish to consider using a saline nasal spray instead.
Saline sprays and drops are suitable to use from birth and are a gentle way to clear up a congested nose, so you might want to try using it before bedtime to help your child sleep comfortably.