Trim the braid off your working thread, leaving the ends long enough so that they won't fray to the knot while you keep working. The forelock braid should have threads that extend the length of the neck. This is largely a matter of personal taste, and can be adapted to suit the model at hand. In the US, real horses usually are done with 20-40 braids, depending on the mane and the length of the neck. There are no rules for the proper number of braids, or whether there is an even or odd number.
More braids make the neck look longer, and shorter braids make the neck look fuller.
Sometimes conformation hunters are braided so that the braids are practically touching. In any case, the braids should start right behind the bridle path and end approximately at the midpoint of the withers, and be evenly spaced down the neck. I use Leather Weld, which is the glue I use for all my hairing. A toothpick and a needle are handy for applying glue and poking small areas. Pick up a braid, and pull on the threads gently to make sure everything's tight.