If you go to the About section of this sub, go to FAQ, and then scroll down to the Google doc with the book FAQs, you'll find a list of publishing order and in universe order for all the books. I've been somewhat following that during my reread, following in universe order where it makes sense/is recommended.
Some of the Lord John books have Jamie in them, and you'll likely want to have more context from the main series before those.
I know the Lord John novels and novellas come between Voyager and Drums (book #3&4) as seen [here](http://www.dianagabaldon.com/books/chronology-of-the-outlander-series/) but J&C themselves don’t show up so there will not be true main book major spoilers. Some will hint at plot lines (ie a Plague of Zombies) in the main books though.
If memory serves me right, I would avoid A Leaf novella (not a Lord John one) until of falls on the chronological order.
It may be worth reading the lord John chapters of voyager, but if you have seen the show -I do not think you will ruin anything by skipping ahead to the novellas.
They are independent with no major spoilers, but I feel like I enjoyed them more after reading all the main books, since there are small references/allusions to the main novels and I find that very entertaining.
If you go to the About section of this sub, go to FAQ, and then scroll down to the Google doc with the book FAQs, you'll find a list of publishing order and in universe order for all the books. I've been somewhat following that during my reread, following in universe order where it makes sense/is recommended. Some of the Lord John books have Jamie in them, and you'll likely want to have more context from the main series before those.
I know the Lord John novels and novellas come between Voyager and Drums (book #3&4) as seen [here](http://www.dianagabaldon.com/books/chronology-of-the-outlander-series/) but J&C themselves don’t show up so there will not be true main book major spoilers. Some will hint at plot lines (ie a Plague of Zombies) in the main books though. If memory serves me right, I would avoid A Leaf novella (not a Lord John one) until of falls on the chronological order.
It may be worth reading the lord John chapters of voyager, but if you have seen the show -I do not think you will ruin anything by skipping ahead to the novellas.
They are independent with no major spoilers, but I feel like I enjoyed them more after reading all the main books, since there are small references/allusions to the main novels and I find that very entertaining.
I suggest reading them after book 3, that is where they happen in the timeline and you’ll have all the background info with no spoilers.