As mentioned, pax arriving in the US clear customs at the first port of entry, Thus, its important to find out where his flight into IAH
With code Orange being in effect, an Australian with US residency coming from Sri Lanka may get a little special attention, so an extra few minutes may be required......that could screw up a connection, be aware of that. Also, something unexpected could happen......a BA
flight into IAD
got held up for about 4 hours last night due to some undiclosed special circumstances. Hope for the best and prepare for some inconvenience due to the world situation.