If you have good content it is worth from day one! Because when you quckly receive many and/or high upvotes you will enter the hot categroy tab. Many people can then see your post which otherwise will fade quickly into Nirvana.

But make sure to read up on all bots first and track their behaviour. I never send a bid without looking at the Voting Power, the Upvote value and - if a bid bot like @booster or @bellyrub - how much is already in the pool.

I have some videos about them but they often change so check out each bot Steemit profile first for the latest annoucements.