yes I might've indeed! Thank you for answering my question, that's exactly the information I was after. Maybe my search through the group didn't yield much results because of that mistake 🤦♂️
One more thing to note, you could have your Tao's landlord/hotel registering you in advance of your arrival (for the day of your arrival) and squeeze in your visit at immigration between your arrival in Samui and your transfer to Tao. It shouldn't take more than 2 hours to get this sorted out in Samui if you have all your paperwork in order.
I'm from Samui. The process is similar as reported in Chiang Mai. 15 days under consideration then remaining 45days stamped on that 15th day (so 2 visits at immigration, must be same office and must be where your address is registered).
The latter is one issue you'll have to deal with before requesting your Covid extension in Samui: having your address registration done in Samui district (either Samui, Phangan or Tao) before being able to apply for an extension at Samui's immigration office. Hotels and other rentals have 24 hours to report your stay at immigration (TM30). So you either check-in at your place in Koh Tao and come back to Samui/Phangan immigration office to make your initial covid extension request then come back again 15 days later for the remaining OR stay 2 days in Samui prior to leaving for Tao and have your initial request done to save one back and forth trip from Tao.
* I'm not sure the Phangan imm. office still operates
* Some people have their full 60days stamped in on initial request but they weren't on their first extension in Samui