Iron: only just after SH21 was finished. Now the building times are long enough, so that two builders can do their work and there’s still iron left to build harpoons.
Food: If I need more, I just swap between TC11 and 20
I didn’t have any issues for along time, but I only have 1 builder.
I’m now having it briefly, since I did the HUnter’s Lodge before the Advanced Food Storage - oops.
I’ve got all of Mine/Farm/House/ Iron Storage/Food Storage converted now, and am researching harpoons. working on regular farm/mines while I accumulate a reserve again.