Hi @fitinfun, the first 30 minutes (HF19) or 15 minutes (HF20) after a post or comment is created are called the reverse auction time. During this time, the curation share of a vote going to the voters increases linearly from 0% to 100%.
When you voted within this time in HF19, a part of the curation share of your vote was given to the author. Therefore, a self-vote at post creation time in HF19 gave the author 100% of the vote value as author rewards. Now with HF20, this curation share remains in the reward pool instead of going to the author.

For the auto-votes, dividing the old voting time by two is a good starting point. For self-votes at post creation time you would get 75% or your vote as author rewards but no curation rewards. By self-voting at a later time, you also have a chance for curation rewards. The timing depends on all other voters, though.