The Community will be undergoing maintenance on Friday January 10 at 2:00pm - Saturday January 11 at 2:00pm EST, and will be "read-only." For assistance during this time, please visit our Help Center.
I too did not find any simple option without using a formula field; however, you can try one very simple solution just create Single Select Field and enter the range of months as options if your range is limited.
Like;
Jan 2020
Feb 2020
…