If i want to timestamp an entry, I use C-c .
and if I want to do this *without* causing it to appear in the agenda, I use C-c !
The second step is pretty handy for me to date my entries in my decision journal.
I want to keep track of when I made a significant decision and my rationale behind it.
But, not something I want popping up in my agenda :)
Timestamps in Org Mode: https://orgmode.org/manual/Creating-Timestamps.html
Decision Journal: https://fs.blog/decision-journal/
Original: https://toots.dgplug.org/@jason/110172780910730038