Accepted pre small claims but no money

[Wreckerd]

Had an issue with a businesses bill. Complained loads. Told him when I paid it I thought it was unfair and intended to take him to court.
Marked the payment as “paid under duress” on the details field of the payment.
Anyway, I did the pre small claims court action letter, he agrees to return £1500 for not doing court. I reckon the court will award me £2500 to £3500 + court fees, so I sent a letter accepting the £1500 and agree that’s the end of it. He received the letter and signed for it 7 days ago.
He has my payment details. No payment received.
How long do I wait before sending in court paperwork?
14 days?
Any advice appreciated

Andy