In the menu, navigate to Illustrator CC > Preferences > General.
Uncheck the box that says Show The Home Screen When No Documents Are Open. Then, click OK.
You're all done! Illustrator has returned to its former behavior.
In this short guide, I'll show you how to disable the start, or welcome screen, in Adobe Photoshop CC. This screen is also known as the Home Screen and used to be called the Smart Workspace.