I was looking at this thread a bit more closely and realised that the same part (the forward fuselage) was spotted at XFW twice, once on the 12th of November (link) and once more on the 11th of December (link). This is leading me to believe that the part on the 11th of December was actually MSN7. Thoughts?
I think you're right.
So we have about 3-4 weeks between each shipment, that sounds about right.
MSN5 will roll out in April and fly in May. MSN6 was loaded into the FAL about 1 month later. Depending on the customer inspections, it should roll out in June or July at last, and fly in June or August at last.