I sit there in age 2 with my market (earned by reaching age 2) in the corner spamming traders to the furthest ally. I then spend a ton of time on age 2 as said traders no doubt accrue > 2000 of gold (have tried switching them to others as well). Of course there’s no way to tell— but often each is hauling > 150 resources at a time— reaching 2K should easily be happening.
I have earned that one but it’s very difficult to do without in game counters lol as with most I did put in a request for that and it sounds like it was put on the list.
I just do the math on how long it will take at that rate, then go AFK and add a couple minutes to it just to make sure.