You don't need to wait for the screen, you can find it yourself. Have you ever changed around your in game settings, such as photo-quality settings, graphics settings, or Lot View options? You can find the "Enable CC" dialogue box hidden among your in game settings
When you're in game click the three dots (that you click to get to "save" and "exit"), click the picture of the two gears (it will say "game options" when you hover over it), In upper right corner there should be s small box asking if you want to display the custom content dialogue box at startup. But you don't need to enable and restart. There's also a little splotch thing (that the game uses to mark custom content). Click that and the box will appear right there.
