For arrival in Bangkok please put both your Test&Go hotel and after "quarantine" address in the arrival card. At minimum have it ready for immigration. When I passed through BKK on the 11th of March this delayed the queue a lot. I even had to scramble and repeat myself multiple times I was not heading to a hotel...
They also have some kind of new form where you have to fill in your details and what scheme you travel on. I forgot to take a photo but basically it is formulated quite badly like your have been determined to be suspected of covid. I assumed after checking it a few times it is more meant to be phrased that they don't know until test come back or you finish your sandbox or AQ.