It will need to be sawed to 3" thick slabs, and then processed in to stock blank sizes
the ends will need to be sealed with Anchorseal or similar parrafin based alternative to keep the end grain from cracking.
They will need to be stacked out of direct sunlight, out of direct wind, but not in a cold damp area
They will need to be stacked on spacers or "stickers" so that air can flow freely around all sides.
They will need to be rotated from the inside out every 3 months or so to be sure that the ones in the middle don't stay too damp.
Next you'll need to figure 1 year per inch of thickness to dry + 6months each if you're in a relatively humid climate.
Most stock-makers hate touching a blank that is less than 10 years seasoned. Yes, it'll be dry in 3-4.5, but the wood then needs to be left for a few seasons to go through all the temperature and humidity changes. This relieves the internal stresses and prevents the stock from twisting or cracking when it is machined.
Yeah, you could have someone slab it, then kiln dry it, but you still have to season it, and Kiln drying kills all the colors in Walnut. It goes from purpled, browns, greens and reds to just a flat dull brown.
