For things that are paid out, I have this:
which you can use as a guide. It sees the affect of if you changed your vote timing (while preserving the vote value).
https://helpienaut.github.io/steem/curation_analysis.html?account=michealb&votedUser=
But yeah, it definitely depends, something you know is popular, you have to weight the early penalty loss against what you think you'll gain from being early.
thanks