I would first make sure we got Iron Working (prerequisite for Samurai, among other things), then head directly for Code of Laws, possibly also via Writing and Currency, not the religious techs.
It's not critical to be the 1st to discover IW, where it is critical to be first to CoL. If there is iron within the range we would normally settle, then we'll settle it, and if it's not there we'll need to acquire it probably by force. And it will be some time before we can build Samurai. Since we have horses we can take the risk of not going to IW first even if we don't have copper. If we didn't have horses, and ended up with no copper, then we'd be forced to put IW first or face a tough climb.