Patent fees are calculated based on the patent year, and each patent year is different. Starting from the filing date, every first anniversary is counted as a patent year.
According to the regulations: no annual fee is paid before the patent is granted. The annual fee will be paid starting from the year of authorization. For each subsequent patent year, the annual fee for the next year must be paid one month before the application date.
According to what you said, the first patent payment year is: 2008.5.*-2009.5.*, that is, the first year's annual fee, and the second year's annual fee must be paid before 2009.5.*. The second patent directly requires you to pay the annual fee for the second year, that is, 2009.5.*-2010.5.*, so you do not need to pay the annual fee before 2009.5.*, saving one year of annual fees, May 2010 Just pay the annual fee for the third year directly beforehand.