If you are after the internal chronological order (the history of the told story) I'm not sure. Some one will know though.
So far as I'm aware:
1. The two Hobbit saga boxes, in release order.
2. The core set.
3. All the adventure and deluxe packs, in release order.
4. The Lord of the Rings saga boxes, in release order.
The print on demand scenarios are a bit more tricky.