This I find to be a rather odd entry into o goshi.
I would think you'd have to be fast, because if my opponent comes to my side my usual reaction is to square myself with him.
This entry I find to be much more useful, using your opponents own momentum to close the distance. I've always attempted hip throws after aggressing toward my opponent... which never works (for me).
What worked last night? Wish I knew, but I don't especially remember the entries (though neither were from the side).