It would be helpful to know why this operation is important because there may be a better way to accomplish the "why" than you might realize.
I can't image a use for having Terminal launch at startup without a window. Not that there isn't one, but I just can't imagine it.

AppleScript can be used to hide a window, but the application first has to create the window (which displays on creation), then hide it immediately. The window is thus only visible for a split second.

You can send applescript code from shell scripts using the osascript command (man osascript).

You can examine Terminal's applescript functionality from within Script Editor.app by selecting "Open Dictionary..." from the Script Editor "File" menu, then navigating to Terminal.app.

Otherwise, I don't know if this is possible from the command line.