toward the back. depending on the length of the lace and the size of the saddle skip some holes so you have enough lace to make it to the end. i tired to skip the area where i estimated the seat clamp would sit, so the lace did not rub on the clamp.
use a needle nose pliers to tighten the laces as you go. i used my thumb against the outside of the saddle to hold the outside lace tight. the saddle does not need to be very tight (it should have some play) or it will break when you sit on it.
the back side of the saddle is more 