If it is possible, we should wait until the employer brings up the topic of the payment. If it is too early, starting talking about the money by you is a mistake, because then you seem to be materialistic. It is better if the discussion of salary starts when you have already sold yourself, that is the employer sees you as a desirable person who is worth taking on.
If the employer offers very little, let him know immediately. However, you can count on the fact that you have to make a statement.