With the /WAIT parameter?
Even if it does, let me rephrase previous post as "a black box will either open (and remain open until you terminate the "target" program) or flash briefly on the screen, to avoid that use nircmd, INSTEAD"
I'm really not familiar with windows scripting/programming but I have PHP knowledge so I added the /MAX parameter after /WAIT using some logic.
Now when I double click on .ai or .eps file the black box opens and remains open until the program completely processes/opens the file. After few seconds, once the file is opened and editable the box DISAPPEARS AUTOMATICALLY.
I don't know if this is how it's supposed to function but it's serving the purpose perfectly!