Excel circular references - I need a formula that will append a list

Hello and thanks in advance,

Scenario:
I need to maintain a list of timestamps and scripting is not currently an option: in order to get a timestamp (a text string = now plus value of A2 ) I am using a version of the following:-

=IF(AND(C2<>"",C2<>0),C2,IF(ISBLANK(A2),"",TEXT(NOW(),"dd-mm-yy, hh:mm:ss")&" "&A2))

this works and creates a static timestamp.

Problem:
I need a formula to enter and copy down immediately below the above formula to create/append/grow a list of timestamps each time A2 changes,
i.e.:
once C2 becomes static - and A2 has changed value - I want C3 to become a static string value, then
when C3 has become static - and A2 changes value again - I want C4 to become static, and so on.....

If someone has a solution please provide it, and, perhaps an explanation?

Likewise if it isn't - please an explanation why?

This is the first time I have played with circular references and I am quite literally going round in circles (like a dog chasing it's tail - ha, ha!) - my initial instinct was that this was possible but I can't seem to get started.

Using Office 365.

Thanks for looking at least