Move date production to separate function
Update error for missing start date
Consolidate if/else to single line statement for inclusive dates
Struggling to use time calculations...
Fix spacing/formatting issues

- Spacing for 'days' vs. 'day', when one day remains caused the whole thing to
  get shifted one space left.
- Spacing for 'TODAY!' was wonky. Applied some formatting to line it up with the
  rest of things.