2when you need one
This only matters if you have decided to build with honey. Nothing else routes through it, so plenty of playthroughs finish without one ever being placed. If you are furnishing a hive base or a jungle house, it is the single gate between a pile of honey blocks and an actual furnished room.
Ivy Chests are the natural route, since you loot them anyway while clearing the Underground Jungle. The Steampunker also stocks it, but only while she is living in the Jungle, so buying one means either moving her there properly or throwing up a temporary house nearby just for the sale.