Are there any ways to make a script(jsx) of a CEP Extension run right after user startup InDesign?

I am going to build a CEP extension on InDesign CC 2015 using Extension Builder 3. The Extension must add a menu to InDesign menu-bar right after user startup InDesign. The issue is that, I don't see any ways to make a script of Extension run right after user startup InDesign. Are there any ways to do that? Should I use SDK for InDesign CC in this case? (because this SDK is not free, we must buy a partner account to download it. See http://www.adobe.com/devnet/indesign/sdk.html  )