I just got the iPhone 6+. I didn't back up the 5 to iTunes before I Hooked up the 6. So the 6 is not current on messages and pictures etc. Is it too late?
Did you have iCloud backup enabled on what I assume to be your old iPhone "5"? If so, then your data should be restorable. Just restore from your iCloud backup when prompted during setup of your iPhone 6 Plus. Having said that, if you're still in possession of your iPhone 5, just do an iTunes backup and then restore that backup to your iPhone 6 Plus. It's NOT too late.