Iphone 14 trade in deposit question

Hello there,

I have just ordered the iPhone 14 pro max directly from apple as a pre-order. I have opted to finance the phone on a 0 per ent interest plan. I am also trading in my iPhone 12 pro max for an estimated 410 pounds credit. I have just checked my finance plan, and it mentions I have to pay a 410 pound deposit to apple until my trade in value can be confirmed once I receive my iPhone 14. I was just wondering do I pay this deposit when my phone ships or does this have to be paid within the next few days/weeks? The phone isn't estimated to come until the middle of October.

Thank you.