That really depends on when you want posts to be published. Do you want them to publish any time of the day or night or do you only want them to publish during certain hours of the day – like 9 to 5 for example?
You need to create a publishing schedule that would publish the number of posts you will be creating in the amount of time that you want them to publish. Using your 30 posts example you would need a publishing schedule that would publish at least 4 posts each day. If that’s any time of the day or night you would want an interval of 335 minutes. If you want to only publish between 7 AM and 7 PM you would need an interval of 165 minutes.
As far as randomly distributing the posts – you can select the random publish option but I am not confident in that option working correctly and have not been able to figure out the bug there.
