After you join the Ads program if you don’t set time slots, the default setting is for pre-roll and post-roll ads to be inserted at the beginning and end of each episode (before and after your audio content).
However, you may prefer other times. And, you may want to consider setting mid-roll slots for new and top episodes, as these slots are popular with advertisers and often bring a higher rate. To manually set/edit ad time slots, please go to the advertising page and click on the “Ad slots” menu. You will be able to set times for pre-roll, mid-roll, and post-roll ads on episodes individually or by batch.
Here is the Video Tutorial
Set Ad Time Slots to A Single Episode
Click the episode title and there will be a pop-up window for you to set the ad time slot.
Edit Ad Time Slots When Publish New Episodes
You can also set the ad time slots up directly when you publish a new episode.
Batch Edit The Ad Time Slots
Select multiple episodes to batch edit the ad time slots or batch delete.