How many days before my visa exemption expires should I visit the Immigration office in Bangkok for a 30-day extension?

𝗛𝗼𝘄 𝗺𝗮𝗻𝘆 𝗱𝗮𝘆𝘀 𝗯𝗲𝗳𝗼𝗿𝗲 𝗺𝘆 𝘃𝗶𝘀𝗮 𝗲𝘅𝗲𝗺𝗽𝘁𝗶𝗼𝗻 𝗲𝘅𝗽𝗶𝗿𝗲𝘀 𝗱𝗼 𝗜 𝗻𝗲𝗲𝗱 𝘁𝗼 𝗴𝗼 𝘁𝗼 𝗜𝗺𝗺𝗶𝗴𝗿𝗮𝘁𝗶𝗼𝗻?

In Bangkok you can go for an extension when you have 45 days or less left on your current stamp <- meaning from 45 days before the stamp expires right on down to the last day it's good for.

In Bangkok you go to IT Square Laksi Plaza 3rd floor. There are copy/photo shops next to the immigration office and you can get in to the building before the mall opens on the ground floor in front by the 7 Eleven then take the elevator to the left up to the 3rd floor..