Another reason to make both versions available at the same time is to avoid alienating your fans.
“What? No print version?”
“What? No digital version?”
Whichever you publish first, someone will feel left out. Don’t miss an opportunity for a sale because you weren’t ready when your fan was ready.
Multi-format sales are slowly bleeding into Amazon. Buy the print version, get the digital version for a discount. Since the digital version has little or now incremental cost associated with delivery, it’s a no-brainer to give anyone who buys the print version a digital copy if they’d like one.
I especially like this option for reference books. Print version at home, because I prefer print, but a digital copy on my iPad just in case.
When you upload all your files to Amazon, be sure you use exactly the same title for both versions, otherwise Amazon will have a hard time connecting the two versions, tying reviews and purchases together.