I produce heaps of podcasts and each show is slightly different.
If it is scripted and you are using a trained professional to do the reading, they should be able to do the recording with minimal stuff ups, and in turn removing the need to do lots of editing. If you are using someone that isn't so great a cold reads, then be prepared to spend time putting together a final product.
My advise is that if you can, be a bit flexible with your presentation. Podcasts can have a few vocal hickups and make it feel much more natural than a very edited piece and generally will keep people more interested in the presenter.
When you do your first recording session, note the time that it takes to do the recording and then budget on double that for the edit. You can make life easier for yourself if you mark edit points as the presenter stumbles to save relistening to the whole thing to find the mistakes. That being said, you will need to listen to the whole thing at some stage to check the edit.
As you do more and get confortable with the format, then your production workflow will speed up. I personally do nearly everything on the fly now like a radio show, but the types of shows I produce don't require editing as it more informal chatting.
Good luck with the podcast and I hope this helps a bit.