OP is flying TG from SIN so the check-in time is determined by TG, doubt it is more than 4 hours ahead. Interling the bags DPS-SIN-BKK is also not possible at DPS checkin due to the 24 hour stopover, so OP will have to clear customs at SIN and recheck bags with TG. Best to ask TG when their check-in opens but it won't be like SQ.