Does anyone know how far in advance these two airlines release their confirmed schedules? I know you can book up a year in advance but I have had instances when my flight time has changed after I had booked before. I guess this is either due to a review of flights due to demand?

 

Secondly as regards cheap saver and promotion tickets, is there any guide on how far in advance these are made available? 

I did book and purchased a ticket on BKK air but they changed my flight and I refused to accept their offer until they found me another flight on another airline flying same times I booked.  Surprisingly BKK were extremely helpful and I might book again on their flights.

they have changed mine before too but i never got that offer

I thought Thai was 10 months but you could always try to book a flight and see how far ahead the calendar is for. As for airlines changing there schedules it happens all the time with all airlines. If you are flying a busy route its more likely extra flights will be added than taken away.