With no (large) images, a stable & reliable connection (upload & download) it is not too hard to test delay times during posting, and get some statistics/experience in hitting specific timestamps.
If anyone wants to go through the trouble – it is possible, esp. in times with low traffic on /qr/.
If you have a known and fixed upload rate, you can even time/compute delay when posting images, depending oon filesize.
All breaks down of course if 8chan is crowded (i.e. when Q posts, during attacks or things like Q & A's etc) – or if you do not have a stable & reliable connection (with no major outages at cloudflare or the web in general).
Yes, there is a "seasoned clockfag" as he calls himself, who went through the trouble.
Why should I? Esp. if I don't have the necessary reliability in connectivity? It's Q's timestamps that matter, not mine (or anyone else's for that matter).