It depends on the time of day and if there are other flights. We've sailed through in 20mins and others it's been 90mins.
But yes waiting for your bags is what takes the longest.
It's not customs that's the problem... it's waiting for your luggage.
Word!
At that time of night you should be absolutely fine, there should be no line at customs. As long as there are no international flights arriving the same time from Asia, then you're hooped.