As I noted a couple of weeks ago, each author is a publishing house unto himself now. For those not in the dying traditional publishing world, this is literally so. It is virtually so regardless of how you play the game, because publishers and agents can only do so much so you might as well operate like the true indie authors.
That means making publishing decisions for yourself. One of them is what format you will publish in, and when you do it: e-pub, print, and audiobook. You should do all three, but you need not do all of them at once. Furthermore, I say that you should not do so. You stand a better chance of overall success by treating each format's release as a separate book launch event, allowing each previous event to push the new one and each new one to promote the previous ones.
What I'm going to do is go with a specific launch order: ebook, print, audiobook. I may break the print section down further by hardcover and paperback, once that becomes something I can bother doing. The reason for the order is this: any errors in the ebook can be corrected and pushed forward free of charge, and the corrected files then be used to for the print book version, which will be the basis for the audiobook VO script.
Now, exactly which thing gets put out when I don't know yet. That I'll announce in a few weeks.