Klarna's due date is always 30 days from the order, no matter when your glasses are delivered (depending on your country, your Klarna payment option may differ).
Your glasses are made individually to your prescription, and delivery takes about 5 weeks. This means the due date can come before your glasses arrive.
What to do if the invoice is due before you get your glasses:
You can move the due date in the Klarna app or by contacting Klarna's customer service. Tell them that your order hasn't arrived yet, and ask them to move the due date of the invoice.
Klarna's 30-day invoice has no interest or extra fees, so moving the due date doesn't cost you anything.
The due date and your right to return:
Klarna's due date is not connected to our 100-day returns and exchanges. Your 100 days start on the day you receive your order. If you return your glasses, we refund the full amount and the Klarna invoice is cancelled automatically.