Why should I apply for a five-year Thai visa at least three months before entering the country?

𝗜’𝗺 𝗮𝘀𝗸𝗶𝗻𝗴 𝗯𝗲𝗰𝗮𝘂𝘀𝗲 𝗜 𝘄𝗮𝗻𝘁 𝘁𝗼 𝗴𝗼 𝘁𝗼 𝗝𝗮𝗽𝗮𝗻 𝗳𝗶𝗿𝘀𝘁 𝗮𝗻𝗱 𝘂𝘀𝘂𝗮𝗹𝗹𝘆 𝘁𝗵𝗲 𝗽𝗿𝗲𝘃𝗶𝗼𝘂𝘀 𝗧𝗵𝗮𝗶 𝘁𝗼𝘂𝗿𝗶𝘀𝘁 𝘃𝗶𝘀𝗮 𝘆𝗼𝘂 𝗰𝗼𝘂𝗹𝗱 𝗲𝗻𝘁𝗲𝗿 𝗮𝘁 𝗮𝗻𝘆 𝘁𝗶𝗺𝗲 😮

Actually on a single entry thai tourist visa you had 3 months from the date it was issued to ENTER thailand and get stamped in for 60 days

BUT

This DTV is a FIVE year visa, so once it's issued you have that long to enter thailand and get stamped in for 180 days 🙂 Being in Japan for 6 months after you get the DTV isn't gonna affect you entering on it in the least

It will burn down 6 months of the 5 year validity as that starts the day they issue the visa, but it's not gonna affect you entering the country on it

I might be over interpreting your statement, but in case your intention is to apply while you are in Japan, please be aware that that's not possible. The embassy in Japan only accepts Japanese nationals and permanent residents of Japan. 🙃

Once you have the visa you can wait as long as you want to enter. You don’t have to enter in 3 months (people’s plans change, etc.). However, when you apply you say you will enter in 3 months (that is the guidance for any Thai visa). They just don’t want a backlog to happen, slowing down approvals for people who are actually leaving in a few weeks/month(s).