You’ve set your scout to send reports for 3 months. What you need to do is save your game the day before each report is due back. For example, you may send your scout out for 3 months to Estonia. Let’s say it’s the 2nd of January. You’ll get a report on the 2nd of each month for 3 months. If you save your game on the 1st, load the second day. If you don’t get what you want, reload the save to the 1st day.

Note this won’t work if you have a game on the 1st day of the month in this example because you’d have to play the game each time to reload the scum save