Can I extend my Thai visa early at the immigration office in Koh Samui?

A user seeks advice on extending their visa, valid until January 31, 2021, asking if they can apply for a 30-day extension at the Koh Samui immigration office before the expiration date. Various commenters confirm that applying early is permissible and beneficial, noting that extensions add to the current 'admitted to stay' stamp, ensuring no loss of days. One user advises considering a 60-day extension due to COVID-19 travel restrictions, emphasizing the importance of applying by January 30, 2021.