Static datestamp by formula?

[retep999]

Hi all,
I'm trying to enter a datestamp from a single cell entry point, and this works fine, but obviously it changes every time $A$2 is changed. (There are hundreds of entries in column "D")

=IF(AND($A$2=D2,$A$2<>""),IF(E2="",NOW(),E2),"")

I need the datestamp to remain static, after new data entry in A2. Any suggestions would be appreciated.

 

[footoo]

https://www.pcreview.co.uk/threads/static-timestamp-without-using-macros.3099014/

 

[retep999]

Thanks Footoo,
I've checked this one previously and it's not what I need. I already have iterations enabled, but what I really need is a way of locking the individual cell in column "E" after the datestamp is added. The formula is, of course, in column "E"