Get first Cambodian e-visa online, flight bkk to phnom-penh. Processing of non-b visa it will takes 5 days to process. Make sure you have your complete documents with the police clearance certificate. Visa fee is 80$. If you process on Monday you will get your visa done on Friday.
เมลานี่ เมลานี่ when I arrived in bkk the IO asked my contract. And I just showed my documents. Better to make a copy of your non-b documents (contract, invitation letter for hiring foreign teacher)