I would uninstall the mods in the reverse order of installation and then run it again and see if it still ctd's. If it does, I would probably uninstall everything and start over. If it doesn't, I would reinstall the mods, one at a time, in this order:
- GWX 16km Atmo
- GMX - Enhanced Damage Effects
- DBSM (Das Boot Sound Mod)
- Conus SH3GWXWS 2.3
Try running GWX after installing each mod and see what happens. You are using JSGME to install the mods, aren't you?
When the campaign starts you are usually instructed to run a five day cruise, then return to port, unless you have started from Konigsberg. Should be in the mission orders at the start. Or don't. Your choice. You can stay out and wait until the war starts if you prefer. If you were to use SH3Commander you could also change your start date very easily.