So, obviously, lots of variables. Having character sheets and colour pallets pre-made helps streamline a lot, as does a plan. And obviously, your shots are going to vary, some will just be headshots, some will have more complicated backgrounds, some will be simpler, some will have multiple characters, others just one. And of course, as you work you'll work out ways to streamline your work even more. And, of course, it depends on what you're considering an episode. Some people consider that a page, some people consider that to be more like the standard webtoon contracted episode which is roughly akin to a weekly manga.
So, based on some slightly older numbers we once worked out here on the forum, a contract for a webtoon in scrolling format (again, remember this was worked out a while ago based on old data, so massive pinch of salt) is around 50 panels an episode, which is around 8-10 traditional pages depending on panelling, and the general consensus is that you would be working this as a full time job of something like 8-10 hours a day at least 5 days a week.
Now, that's the professional standard, and very few hobbyists will publish that much at a time. Much more common is a page or two an episode, or closer to 10 panels, but again, this varies massively from person to person. It's about finding what works for you. Personally, I do an entire big chunks at a time, which takes me anywhere from a week to 2 weeks working for 4-6 hours a day and then breaking that up into episode chunk that's usually between 5-10 episodes depending on good stopping points.
But, in the end, you have to find a rhythm that's right for you. Dive into it and see how long it takes you to make episodes and experiment a bit. See if you can find easier and more efficient ways to do it. You'll speed up naturally with time, and you should try to be several episodes ahead of where you're posting to allow yourself time anyway. You'll probably find lots of time saving hints around, like doing things in batches (all your sketches, then all your inks, then your colours, for multiple episodes at a time) finding ways to cheat the details and learning where to focus the quality and time (not every panel needing to be as perfect and details, saving that for impact panels) and so on.