I searched for and found an old thread i stared last January 29 titled "ESPN announces softball schedule" (or something like that). So ESPN will probably announce the 2015 schedule in late January as well. Not sure about the SEC network (do they play softball in the SEC?) or more importantly the Big 10 network.
It's funny you all posted this because just last night I did a DVR search for "softball"! Alas, it didn't turn up anything but it won't be too long now until games will start popping up. I really hope that the SEC network will air some early ones!
Here in So Cal games start the first week of February. Try going to the individual schools websites. Sometimes their schedule will show whether the game is projected to be televised.