As far as I know, the 'custom' order works like:
-Rough in your specs and work with your dealer to get the basic instrument lined up and an estimate for the work. If you have any oddball or specifics, this is the time to bring that up and your dealer will find out if it's do-able or not. Once you have that in place, you'll be asked for a deposit and you're in queue...with a very rough estimated timeline.
-Once they're closer to your build, Dingwall reaches out with an actual work-order document for you to confirm, make sure you get eyes on this and look it over personally. This means they're close to doing your actual build, and want to confirm that everything is solid. From here, you make sure they've got exactly on paper what you want. Check the fine details. If you've fussed a few things around, you'll get new pricing information on those changes. In my case, that was a switch from a flat black one-ply pickguard to a gloss 3-ply black, and I also noted that the Luminlay markers I requested didn't get noted, so that got fixed.