Does it matter what time of day you publish your podcast episodes?
In short: publish either in the morning or as soon as possible.
Please listen to my previous episode about the best day of the week to publish for considerations on that. But this episode is only about the time of whatever day you choose.
Like with your publishing day of the week, consistency is most important. Try to publish at the exact same minute of the same hour on every publishing day.
This helps some legacy systems, including Apple Podcasts, to learn your publishing schedule so they know when to expect new episodes and can catch them more quickly when you publish. (This legacy and resource-intensive process can be replaced with the much faster and resource-conserving Podping protocol in Podcasting 2.0.)
All good podcast-publishing tools will let you schedule when your episode publishes. (So if your publishing tool does not allow scheduling, get a better tool!) And when you know what the published URL will be (as most tools will show you even before you publish), you can even schedule your initial promotion, like posts on Facebook, Twitter, Instagram (through a Business account), an email newsletter, and more.
Just ensure any caching system you use will also automatically update when you publish the new episode. (Most of them do anyway. But watch out for offsite caching systems like Cloudflare.)
2. Usually mornings for your majority audience
So what is the best time? Look at your podcast stats to see how your show performs in different countries and regions. I suggest usually publishing in the early mornings for the time zones of most of your audience. For example, I publish The Audacity to Podcast at 6:00 AM Eastern Time, which is 3:00 AM Pacific time, making the episode available for most of my American audience's morning routines.
Remember these time-zone differences, especially if you're behind the time zones where most of your audience is. For example, 6:00 AM in California is 9:00 AM in Florida. So publishing at 6:00 AM Pacific Time might be too late for the audience in Eastern Time to catch the episode before they start their daily routines.
3. ASAP for urgent content
If you have truly urgent content, then don't worry about being totally consistent. Just publish the episode as quickly as you can!
For example, I once hosted a podcast that discussed a TV show. We did two episodes every week: a short “initial reactions” episode right after the TV episode aired, and a longer “full discussion” episode midway between TV airings. (Aside: it's great to be in Eastern or Central Time for TV aftershow podcasts because you get the first viewing and largest audience since most TV shows air simultaneously in ET and CT.) We recorded that “initial reactions” episode 15 minutes after the TV show aired, and we would live-stream it, too. Then, we would rush to publish it as soon as possible on the same night. We almost always had it up before those in Pacific Time even saw the TV episode, so our podcast episode was already there waiting for them.
Although some legacy apps (that is, those that aren't using Podping from Podcasting 2.0) might not always catch these ASAP episodes quickly, your audience might come to expect them and might be eagerly manually refreshing their apps in order to catch your episode right away.
4. What about after-work content?
You might think that if your podcast is not about business or targeted toward business people, that you should postpone publishing until the afternoon or evening. But I still recommend mornings even in these situations because business people often like to consume non-business content while at work, or commuting to or from work.
In other words—and this applies to this whole concept of timing—don't worry about trying to perfectly time when your episode publishes. Simply stick to mornings for consistency, or as soon as possible for more time-sensitive content and your audience will listen when they want, as long as your episode is available by that time.