Automatic timestamp and protect when data is entered multiple cells

I'm looking for a timestamp to automatically appear in column D when data is entered in columns A, B, and C (so nothing appears if all 3 cells are not filled). In addition, I want those 3 cells to become password protected once data is entered.

This is what I have in column D:
=IF(AND(NOT(ISBLANK(A4)),NOT(ISBLANK(B4)),NOT(ISBLANK(C4))),NOW(),"")

I have managed to get all of this to work out, except that the timestamp all have the same time and updates with the real-time instead of when it was entered.

I have read somewhere that I may need to go to, Tools => Options => Calculation and check the Iteration Box. I have also read somewhere that I may need to go to, Data => Validation => Settings, select List under Allow and select the timestamped cells under Data. Neither have worked!

I've attached the .xls. Please help! Thanks in Advance.

You'll need a macro running in the background because NOW() will update everytime the sheet updates, so it isn't appropriate for a "timestamp". A macro will need to compare the 3 cells of data and insert a real timestamp for you in column D when all 3 cells are not blank.

I would suggest you post the question in the PROGRAMMING forum "Timestamp/Protect data when 3 adjacent cells are complete".

Those guys are awesome with the VBA. You might even post a sample workbook showing your actual layout and sample data.