What do I do? I

I just got this chunk of wood from our property , it's a royal ponciana tree that had been rotting from the inside out, bottom up for years. And they finally cut it, I was able to save me a big piece, about 4 feet tall and 12 inch in diameter, I wanna mill it into sheets, roughly 8wx10hx1/4thick for scroll saw projects, I have no experience doing this, besides the obvious (cuts and trim) what would it be the first step that I should take? Let it dry? Or start to rough cut AND THEN let it dry?, thanks for any advice?