Dates and months and all that are a little tricky. Your months appear to be formatted as text and, as such, will sort alphabetically as text does. There is no custom sort to sort text any other way.
Two ideas, the shortest one first:
Idea 1: Make a new column that will be the month as a number.
- Insert a new column
- Formula in this column will be =MONTH(A)
- Sort by that column
This may be your only choice if you are using a pop-up for the month names.
Idea 2: Format column A as Date&Time.
As Date&Time, they will sort by date and time. It is easy enough to format column A but it may cause you other problems unless you do some more work. Column A will be displayed as "months" but each will actually be a date&time value with a month, a day (the 1st of the month), a year (the year you entered it into the table or formatted it as a date) and a time (12:00AM). January entered this year and January entered next year will not be the same January and they will not sort together. You might consider doing away with the Year column and displaying month & year in the first column, formatted as January 2015. Here is how I would go about doing that:
- If you formatted column A as Date&Time already, format it back to Text
- Insert a new column C temporarily
- Formula in C2 =DATEVALUE(A2&" "&B2)
- Fill down to the other rows to complete the column
- Select and copy all the cells in C
- Paste Formula Results into column A (it is in the Edit menu)
- Delete column C
- Format column A to show as January 2015
- Delete column B (Years)
- You can enter months and years in M/YY format in the future versus typing out the month name.
Edit: A third idea
- Format Column A as Date & Time
- Sort
- Format it back to text