Once the recipe is added to the haikuports repo, you either have to wait for a Haiku dev to manually build and upload it, if you use the (at the moment default)
http://packages.haiku-os.org/haikuports/master/repo/x86_gcc2/current
If you use the (at the moment still) experimental repo
http://eu.hpkg.haiku-os.org/haikuports/master/repository/x86_gcc2/current/
it’ll appear there automatically after the buildbots sucessfully created the HPKG from the recipe.