The correct approach would be finding posts that will naturally encourage conversation. The only advice I have here is being careful not to post the same thing on many different accounts and subs, since duplicate content will look like spamming.
Reddit's Contributor Quality Score (CQS) is what you should focus on. They use this to make sure only accounts with good activity are allowed to pass there filter. Focus on making and posting comments first then focus on doing upvotes and hopefully receiving some then focus on chatting with a few people then try doing your first post in the smallest subreddit in your niche with less restriction and move your way up.
Ive also found that timing is not important as much as the fact that the initial commenters have something interesting to say. If the comments seem forced and the post looks like a blatant advertisement, then people will just skip over it.
