I'd be inclined to put the shim slot opposite the stem clamp slot, but I don't think it makes much difference.
This, my Thomson shim instructions say to face the slot forward, opposite the stem clamp slot, but I can't see anything breaking if you do it the other way.
This, my Thomson shim instructions say to face the slot forward, opposite the stem clamp slot, but I can't see anything breaking if you do it the other way.