Can you extend your tourist visa 29 days before it expires in Thailand?

Hi!! Can anyone tell me if its correct that you can extend your tourist visa 29 days before it actually runs out?? Beacuse now i was told by a lawyer on Phangan that if its earlier than 14 days before they wont give you the new stamp from your original expire date. Wouldent want to waste the time or money going to Samui now if i dont get the new stamp from the 4th of feb as it says in my passport. Apreciate the help🙏