Welcome to iboats!
Sounds like a sizable undertaking. Honestly, you should be able to tell US how long you expect it to take. If you haven't plotted your course, planned your refueling stops based on the boat's consumption and the '1/3 rule'; and determined where you'll make your overnight stays,.. you may not be ready for this. You should be able to guesstimate the trip using your nautical charts, even before you do your detailed float plan.
What's your boating experience, and (because I'm curious) what makes this a custom boat?
My .02