Open a new spreadsheet in Excel. Type the valid dates for the drop-down in a single column. Do not leave blank rows. You can also use a separate worksheet -- if you do, select the cells, select ...

2] Shift the Excel cell down by clicking and dragging Move the cursor on the edge of the cell that you want to move down until you see a double arrow. Now, drag the cell down.

Simply type a date in a cell and drag it down. After that, Excel will fill the dates in increasing order automatically. If you want to fill the dates with a certain gap between them, let’s say ...