How long does it take to obtain a non-B visa in Vientiane and when can I book my return flight?

Having to go to Vientiane to get my non b visa this next week. I see it takes about 3 days to get… I’m wondering if anyone has any experience on if I’ll get the visa that third day in the morning/noon? I’m need to book my flight back and I’m wondering if a 2 o’clock flight will be late enough or could I still be waiting for my visa by then?

Thanks