Adobe has a little text file that will suppress the welcome screen for some of its products:
Troubleshoot the Welcome Screen
The instructions are for Adobe Creative Cloud 2014 (and randomly the suggestion for Adobe Creative Cloud 2015 is to use the GUI to disable it via checkbox instead of having an automated scripted way).
If you want to keep using the old automated scripted way in Adobe Creative Cloud 2015, here is the new path for InDesign:
/Library/Application Support/Adobe/Startup Scripts CC/Adobe InDesign
And the new path for Illustrator:
/Library/Application Support/Adobe/Startup Scripts CC/Illustrator 2015
Photoshop doesn't seem to work the same way. I haven't found a solution for that one yet.
I don't know how many people use Adobe Muse, but Adobe Muse isn't solved in quite the same way. You have to put a helloPrefStore.xml file in ~/Library/Preferences/Adobe/Adobe Muse CC/2015.0 and the file contents should be:
<int type='signed' size='32'>2</int>