Hard-wax oil, a lint-free cloth, and the patience to do thin coats. Wipe on, wait twenty minutes, wipe off everything the wood has not taken.
When
Once when it arrives, once a season after. If water stops beading on the surface, it is asking early.
Joinery needs nothing — no screws to tighten because there are none. If a joint ever loosens in dry winter air, it will close itself when the humidity returns. Old trick, old wood.
