Thai pass

[Mancs]

You don't need to have actually payed for your flight but you need to know the arrival flight number.

Though as it's a 15 day window to arrive (from June 1st) I doubt IM are that bothered about the exact flight number:

You can apply up to 60 days in advance of your trip and the approval QR code is valid for a 15-day window, comprising your intended date of entry +/- 7 days either side, without the need to upload new supporting documents.

https://mainlymiles.com/2022/05/20/t...tant-approval/