today and last week the check-in in Bangkok was a disaster: baggage drop queue for 40 minutes waiting. But it is not the capacity of the airport: Air Asia Thailand was only prepared to the mass of people with two ground staff for one baggage drop counter and another two to three international check-in counters from 6pm to 7 pm. Although Air Asia has 15 counters available in Bangkok, they opened only 3 or 4 counters.
There is no point in checking in before in Bangkok, because you might wait even longer in Bangkok. Hopefully they work on resolving things!