Macro to Time Stamp Based on Drop Down in Worksheet

[Kyhosa]

I have a workbook with 2 Worksheets. The "SMT Status" sheet shows what product is currently in production, what is up next, and what is after that.
The "Changeover Log" sheet, is where I want to start getting time stamps of changes made on the first tab.

In more detail what I am looking for (SMT Status tab):
-Drop down in Cell C8, C12, C16, and C20 gets changed to "Down - Changeover" it will
-Find the next available row, Apply the current date to column A of Changeover Log
-Copy the number in the cell above the drop down(C7, C11, C15, and C20) and paste in column B of Changeover Log
-Copy the line number from Column B (1-4) and paste into column C of Changeover Log
- Add time stamp in Column D
-Then when Drop Down in cell C8, C12, C16, and C20 changes to "Running - online" then it will add a new timestamp to Column E
- The only challenge with this is the above cell value will be a different value compared to what was previously entered into Column B

Attached is the spreadsheet

Thank you!