1. Disable gdm at boot:

    sudo dpkg-divert --rename --add /etc/init/gdm.conf
   

2. Authorize users to start X:

    echo "allowed_users=console" | sudo tee -a /etc/X11/Xwrapper.config 
   

3. Automatically start X after login on tty1:

   In your .profile or .bash_profile, add:

    if [ -z "$DISPLAY" ] && [ $(tty) = /dev/tty1 ]; then 
        startx
    fi
   

   Logging in other tty will not start gdm or X.

See also this question on serverfault.

1. Disable gdm at boot:

    sudo dpkg-divert --rename --add /etc/init/gdm.conf
   

2. Authorize users to start X:

    echo "allowed_users=console" | sudo tee -a /etc/X11/Xwrapper.config 
   

3. Automatically start X after login on tty1:

   In your .profile or .bash_profile, add:

    if [ -z "$DISPLAY" ] && [ $(tty) = /dev/tty1 ]; then 
        startx
    fi
   

   Logging in other tty will not start gdm or X.

See also this question on serverfault.