It is complicated with bike, I did it in Vientiane and rode by the Mekong to Savannakhet, apparantly its easier with a car but there are some paperwork. You have to own the vehicle, cannot be on downpayment.
I went past 9 am and there was a little kew outside so I drove around had a coffee and came back about 10. Then most of the kew gone and it took me 20 minutes to give my application.
Next day to pick up they had opened earlier than announced so I could go straight to the window.
I went on my own motorbike so nice to have that freedom, went straight to the border and no problems.