How to sort date fields customized by expressions

Summary

Need to reformat date fields customized by an expression in order to sort the data in chronological order, by month.

Content

Using the TBE Reporting Tips & Tricks Vol. 1 doc, I created an expression to customize a date field. I wanted to include only the year and month in which candidates applied to a req.

Here's my expression:

YEAR([REQU|REQU-REQU_CAND|dateApplied]) + "-" + MONTH([REQU|REQU-REQU_CAND|dateApplied])

For any candidates who applied in March 2018, it would display as 2018-3 (April = 2018-4, etc). I used this to create a line graph showing the # of candidates who applied in each month.