How do I calculate the day count for renewing my Non Imm O retirement visa extension in Thailand?

Can you clarify for me how CW Immigration does the day count determining the date one should attend to get new 12 month extension. I have Non Imm O for Retirement for past 3 years. My understanding is that I need to attend 45 days prior to the expiry date of current Extention. This is 14 November. So my count would be 31 days in October and 14 days for November makes 45 days. Therefore I attend on 1 October which I had done in the past including last year. However the IO last year said it was only 44 days (but she did the Extention). So do I go on 30 September instead of 1 October? Thanks.