Does my calendar have to start in January? No. It can start in any month.
How starting calendar months are set
After September 31, the calendar starts automatically in January of the next year. Otherwise, a calendar adds 45 days to the current date and starts at the beginning of that month.
Or start your calendar in ANY month:
After you enter the calendar product, add &Month=5&Year=2024 to the URL you can change the start date. In this example, your calendar's first month will be May 2024.
https://www.dotphoto.com/product_builder.asp?PID=225&AID=0&IID=&Month=5&Year=2024