If you want to customise your Adobe Illustrator CC 2015 splash screen, you just need to replace a couple of files.
I’m a Mac user and to change these files, I navigated to Applications > Adobe Illustrator CC 2015 and right-clicked on the main app icon. From there I clicked Show Package Contents > Contents > Resources and pasted in my two files. I replaced the originals, that’s up to you.
Here is my new splash screen:
Here is a zip (1.6MB) containing my new Adobe Illustrator CC 2015 splash screen at 2 sizes if you want to use this graphic yourself.Illustrator Adobe, Customisation, Graphic design