Where can I extend my 30-day visa in Bangkok and when should I go?

The user is looking to extend their 30-day visa while living in the Bangna area of Bangkok. They seek guidance on the best immigration office location and whether they can apply for the extension before their current visa expires. Comments clarify that they are on a visa-exempt entry stamp, which allows for a one-time extension of 30 days for 1900 baht at the IT Square Laksi immigration office. It is also noted that they can apply for the extension at any time before their current stamp expires without losing any days.