How do you tell if chocolate wafers are old? The bags do not have an expiration date on them.
I would just taste the chocolate wafers to find out if they are too old to use. Chocolate has an extremely long shelf life. Even if the wafers are discolored with white or grayish "bloom" you can still use it.
The only reason I wouldn't use the candy wafers is if they have a rancid taste to them.