Google has just introduced two new search operators – before: and after:
Here is what @searchliaison tells us:
The before: & after: commands return documents before & after a date. You must provide year-month-day dates or only a year. You can combine both. For example: [avengers endgame before:2019] [avengers endgame after:2019-04-01] [avengers endgame after:2019-03-01 before:2019-03-05].
If you provide only a year, before: & after: translates those into full dates that work, such as follows: [before:2018] = [before:2018-01-01] [after:2018] = [after:2018-12-31].
You can use either dashes or slashes in dates. Both of these are valid: 2018-12-31 2018/12/31.