I've contacted local Thai consulate beforehand and they've asked to provide them adjusted flight confirmation and Sha plus hotel confirmation for the desired dates and then they can adjust my pre-approved TP for Test&go scheme.
Adjusting the flight is not an issue in my case, but the hotel...let's see if they can do it... But adjusting the QR doesn't seem to be a big deal for the embassy to what I've heard from them yesterday (4th), was quite surprised, didn't know this option exists at all