I'm wondering if anyone can help;

I'm arriving at BKK on QR829 from Hanoi at around 6.30pm on a seperate ticket. I'm connecting to EK384 in Economy which departs at 1.35am I am thinking that once clearing immigration, collecting luggage etc. I will be at BKK departures around 7.30, maybe 8pm. Will I be able to check in for my flight at this time? I know the standard is 3 hours before departure but since Emirates has a flight leaving around 9.20pm, will check-in be available for my flight as well? I'd rather check in early and head airside than wait in the check in area for two/three hours.

Thanks for any help! ^