If you are on flt 176 from NRT to DFW you should not have any problems because of the early arrival time and there are not many other international flights arrving at that time. However, if you are on flt 60 it could get a little touchy because if I recall I believe you have an LGW, CDG, FRA, and possibly ZRH that all arrive in that 2:30p to
4:00p time frame. At times I've waited upwards of half an hour to clear customs.