@Danny *********
, No, you have to wait about 2 months to apply for a 1-year extension.
Most offices accept your long-term extension application when you have 30 days oe less remaining with your stamp. Some including Bangkok, Chiang Mai, and Phuket, accept within the last 45 days with the stamp. A few might have shorter window. But no office has longer window than the last 45 days under normal circumstance.