If JBJ can hit like his plate discipline suggests, I think he might find himself hitting leadoff before year's end. My money is on Shane in the 1 spot until then.
With Pedey 2nd and Papi 3rd my bet is something like:
1. Vic
2. Pedey
3. Papi
4. Napoli
5. Nava/Gomes
6. Xander
7. WMB
8. AJ
9. JBJ
This is obviously, of course, if Drew doesn't return. If Stephen comes back, I'd hit him 7th with Xander shifting to 3B.
I'd be fine with AJ and JBJ getting flipped in the lineup but I think Jackie, if he can hit decently in his rookie year, would provide an opportunity to get a good OBP guy in the 9 hole so that there can be someone on base for the top of the order when the lineup turns over.