I have a similar situation to face in the near future. To paint the 1/48 B-29 with black primer, I'm going to do it panel by panel. Paint a panel, get it evenly cvered, move on to the next panel. Each sucessive coat will be done the same way.
When painting large airframes like these, it's tempting to want to cover it in large areas. Doing it that way will increase the risk of the paint drying on the way to the model's surface (especially if you're using acrylics). You'll have to hold the brush farther away, & spray with a higher paint volume.
I painted my 1/24 A6M2-N Rufe panel by panel. If you look at photos of real aircraft, the paint coverage is not completely even. Painting it one panel at a time is almost like "painting in scale."
(Of course, you could do as I jokingly said about painting my B-29 and "Get a Wagner !)
Hope this helps.