If you're using windows, just edit the shortcut. Rightclick->properties. There's an option there to tell it how to run, it's normally set to 'normal window', set it to 'maximised window'. Don't know if the wording is spot on, since I'm on a Dutch version of Windows.
If you're on a Mac, then I don't know if you can change that in the shortcut or whatever it's called on there.