...unless delaying it could give you more information/benefit.
I think you play cartographer first, then farming village, then cartographer. I've never run into this exact situation, but in situations where i have have 2 x apothecary + cantrip, I play the cantrip in between, so the apothecary sees more new cards and less of the same ones you just put back.
Hmmm. I like the general principle, but I'm not sure I like the specific application.
The thing is, Farming Village COULD be more than just a Cantrip, which is what makes it unlike your general rule. But if you play it after one Cartographer or the other, it WON'T be just a Cantrip -- unless you have to discard everything.
The thing that will give you the most ability to cycle bad cards out of your deck is presumably FV->Cartographer->Cartographer. That way, if your deck does start off 2xEstate, you cycle them away with FV just the way you would with Cartographer, but you also get more "depth" out of your Cartographers. So, I guess I'd do that if I thought my deck was super, super bloated.
The thing that will give you the most ability to get the one card that you absolutely need is Cartographer->if you didn't find it already, Cartographer->FV. And presumably with the Cartographers, you drop every card if it's not the one card you need. It's a little hard to see what that one card would be, besides Possession. Tactician, maybe? Library?
If you lead with Cartographer and you do top-deck a card that you want, but it doesn't just make your turn, you're done, you're great, then I agree with you: Cartographer, FV-to-pick-up-the-card-you-want, Cartographer with more "depth."