Thank You for the tips @jonno-katz - they're really informative!
The perfect timing issue is even more complex to my mind - as long as steemit is international project and covers basically all of the timezones.
Still, >25% of steemit users come from US (according to similarweb info) - so relying more on US time zones seems logical IMO in case Your post is not geo-targeted or not in english.