Soffit before siding?

[grover]

Hardie lap siding with corner trim boards.  I'm thinking the soffit needs to go up first so I will know how far up to go with the corner trim.  There will also be a horizontal band board on the gable ends.  Another question what is the best looking style of soffit with lap siding?  Forgot to say...I have a 1 foot overhang on all sides.

[MushCreek]

I did my soffits first. I then calculated the distance, figuring out how many rows of siding there would be, and cut the top trim board to keep it all even. I didn't want to end up with a skinny (or fat) top plank. Once the top trim board was up, I could cut and measure my corner boards. I did a band board on the gable ends as well, and I cut a 15 degree reverse angle to make a drip edge above the siding. It's fun (NOT) ripping 5/4 Hardi trim. My gable ends are a bit different, since I went with raised heel trusses, but it looks fine now that it is all coming together. My eave top trim and gable band boards don't line up, but I have massive roof brackets at the corners, so it isn't noticeable.

[MountainDon]

Soffit first. You will likely have horizontal 2x nailed to the wall with the lower edge at the same height as the lower edge of the fascia framing (subfascia). With nailers spaced between the two wherever there are rafter ends/tails. Nail the soffit to that structure. Fascia could then be next.

Then if you plan on a frieze board (horizontal trim board under the soffit to wall joint.)  nail that to the wall up against the soffit where it meets the wall sheathing. If no frieze then install the corner and window / door trim. Siding is next. Then caulk the ends and mid joints IF Hardie still recommends that. They did when I did ours but I seem to remember there might be a change with the newer product. Or I have imagined that. Anyhow follow the present instructions to maintain the warranty.