You want to maximize the percent of the reward which comes back to you, while also maximizing how many shares vote after you. The percentage you keep increases linearly from 0 to 100% until 30 minutes after the post.
So there is no set ideal time, you have to work it out based on when everyone else is voting. Honestly I don't think anyone but orcas and whales should care about curation rewards anyway, they're trivial for small accounts.
Right. Thanks.