I'd like to extend my visa exemption +30 days. When this is done at the local immigration office - if I go in say a week early - do they extend from that date onwards, or will the extension be effective once the current one expires?
TLDR : Answer Summary
If you visit the local immigration office to extend your visa exemption 30 days before it expires, the extension will be applied to your current visa exemption, meaning that they will add the additional days on from the date of your visit, rather than waiting for the current visa exemption to expire.