You are absolutely correct you just drag the formulas over and they will fill in and add months over to the right. You just need to make sure the headers are the months in “mmm yyyy” format like it is already.
You also dont have to only enter values in January 2022 you can overwrite the formula to input a value of your choosing for each month because sometimes different months will have different values, and the following months will fill with the new value based on these formulas.
You can reset this at the beginning of the new year with information like Heather talks about in Getting Ready For New Year