Reading this post "Understanding Apache Access Log" it refers to http://httpd.apache.org/docs/1.3/logs.html which says
%t is the time the server finished processing the request.
By this I understand that a line in access.log will not be written until the request has been served by the server. So if the request takes one minute, the timestamp will be one minute after the server received the request.
But, the above doc is for Apache 1.3. Reading this one http://httpd.apache.org/docs/2.2/mod/mod_log_config.html it says
%t Time the request was received (standard english format)
Now understanding that based on the above example, the timestamp is referring to when the request was first received by the server. But if so, then Apache would need to update access.log yet another time when the request has been served. Or maybe wait to update access.log until the request has been finished, but I doubt that since I would expect the events not to be sorted by time - but they are (making the first explanation more reasonable according to my understanding.
So which one is correct, finished processing or received - or both depending on version? (Or, what have I not fully understood...)