I don't think an early trade post in a foreign civ is worth much, unless you can stack it with other modifiers. +3 is meh.
If you want a fast path to invasion, that's a different story. Speed is everything. But if you aren't playing a conquest game, not only is the +3 not worth it, but you're giving a potential enemy a nice path to your front door. Note: this can work to your advantage, as the ai will use the road, so you can set up a nice killing field.
Rather, I'd use the first trader to both start building roads in my kingdom, and to increase food/production where I most need it. If I'm invaded, I'd rather have roads connecting my own cities so I can move my troops faster within my own borders. Plus it speeds up builders.
If you want a fast path to invasion, that's a different story. Speed is everything. But if you aren't playing a conquest game, not only is the +3 not worth it, but you're giving a potential enemy a nice path to your front door. Note: this can work to your advantage, as the ai will use the road, so you can set up a nice killing field.
Rather, I'd use the first trader to both start building roads in my kingdom, and to increase food/production where I most need it. If I'm invaded, I'd rather have roads connecting my own cities so I can move my troops faster within my own borders. Plus it speeds up builders.