I didn't know that I shouldn't vote on posts older than 1 day. What is the reason for this?
There is basically a mechanics (curation curve) that lowers the rewards for late voters after 24H. It used to be 5 and 15 min :) . This is something that initially was implemented to incentivize content discovery and rewards the ones who discover it early and voted early, but in practice it was botted a lot and not achieved its goal. Then it was pushed to 24H, to keep at least some incentive for early content discovery, but remove the advantage that bots had voting in 5 min window, and level up the game for humans :)
I didn't know that, now I understand. So now, votes on a post by different people within 24 hours do not create timing differences in terms of revenue advantage. Is it right to vote within 24 hours the only criterion?
Yes all votes in the first 24H on a post have same CR.
Curators will get higher CR, if there is more votes after the first 24H, so you might look into post that might do this, but honestly now I don't pay to much attention to this, as the difference is small, and just follow the first two rules, vote in the first 24H and don't go bellow 80%. This for majority of the post, if I see a post I think deserve some love I don't mind if it is older than 24H. Just know these things, and then it is up to you how to act, and observe how will it impact your CR.
Got it, thank you for your detailed explanation. I felt once again that I voted for the right witness