Can I enter Vietnam earlier than the arrival date in my visa approval letter?

No, you cannot. A later entry is allowed but an earlier entry is not. In case you change your plan and want to enter Vietnam earlier than the granted arrival date, you are recommended to apply for a new visa approval letter 

Posted by: Vivian Ng | June 2, 2015,7:08 am
Due to the effect of Covid-19, we currently stop providing visa services for foreigners until April 15, 2020. We will update the newest announcement soon. Many thanks.