Is there another use for Ivory?
There are a couple million ivory worth of late-game unicorn tech tree upgrades. But even those aren't anything to worry about. By the time you unlock them you'll probably have the ivory to buy them without any special effort.
The caravanserai workshop upgrade also takes 10k ivory. But again, by the time you unlock it you'll probably have the ivory.
Mostly it's just the naga trade, and there's only a very small window of the game where that's useful. There are too many other far-more-important uses for gold than to waste it on trading with nagas just to feel like you're not wasting ivory: temples, trading posts and the zebra/dragon trades. But I suppose if you haven't unlocked any of those, go for it.
OK, I'm trying a new strategy.
The main idea is that once you hit the point in the tech tree that your next tech would be Theology, you just stop.
Stopping at Theology means no harbors or trade ships, which will significantly reduce your storage capacities, and therefore reduce the number of everything you can build. It also means no
mansion from architecture, which probably means at least 10 fewer kittens when you reset.
On the bright side, it does mean skipping out on the starchart grind. But I think you might have a difficult time getting many kittens stopping at theology. It might be a decent strategy if you're planning to do a first reset for karma only. But if that's your goal I'm not sure why theology is your target. What do you want faith for? You won't be benefiting from the culture upgrades because you won't be needing manuscripts, you won't need the science upgrade because you've stopping at theology, the happiness bonus is very small, and the only thing that leaves is the production bonus from solar revolution. But your run probably won't be long enough for that to make much difference. And that's assuming that you're even able to unlock solar revolution. Even in the time it would take to push to architecture and then resetting with 90+ kittens your faith bonus would probably only be worth a 5-10% or so production bonus. I suppose it could be more than that if you're afking for days with a macro to accumulate faith. If you're only aiming for a karma-only reset, you could probably stop at steel and be ok. Assuming it's your first run, resetting with 40 kittens is enough to get a +11% happiness bonus from karma. It takes 50 kittens to increase that bonus to +12%. Even 70 kittens is only worth a +14.something bonus. There's not much difference between resetting with 40 and 70 kittens.
The next significant threshold is 71 kittens, at which point you start earning paragon. If you're not going to go for that you may as well stop at whatever point is comfortable after reaching 40 kittens.
On my second run
If you already have karma, the bonuses listed above would be even less. Having karma at all is worth a +10% happiness bonus. After that, each point is only worth +1%. So if you reset on your second run with 40 kittens you'll only get about a +1% happiness bonus from it. Unless you're on your first run there isn't much point resetting before 71 kittens.
By all means, go for it and let us know how it turns out. But looking at the way reset bonuses work, I think theology is probably not a great stopping point.