, do you know if I have to show proof of residency at Chaeng Wattana immigration office? I forgot to register at Samut Prakan when I came in, so I'm want to use Chaeng Wattana instead?
, he probably is. But the van leaves at 1:30 when the consulate opens. I jump in a cab to the border, get an airport van. That way you are back in bkk at 9pm.
If you want to fly, why don't you get the AirAsia from the airport in Vientiane? Nok Air means you still have to travel by land and you have to wait one more day anyway as it leaves when the consulate opens.