Most itineraries give the Zambian bank of the Zambezi a day and a half. Fly into Livingstone, walk the paths, photograph the curtain, jump off something the next morning, fly out. It is enough to say you have been, and it is why so many people come home describing Victoria Falls as a viewpoint rather than a place.
The trouble is that this is not one attraction. It is three landscapes stacked vertically on top of each other: the wide, slow river above the lip; the curtain itself; and the Batoka Gorge below, where the Zambezi stops being scenery and becomes whitewater. Each of the three opens and closes on its own schedule, and that schedule is set by the river rather than by the calendar. Get the order wrong and you arrive to find the island shut, the rafting cut to half a run, or the viewpoints replaced by a wall of white spray.
What follows is a four-day frame for the Zambian side, with the pivot points marked - which days swap, and what decides.
First, ask what the river is doing
The Zambezi peaks in March and April, drains steadily through the dry months, bottoms out somewhere around October and November, then begins to rise again with the rains. Every decision below hangs off where in that cycle you land.
Recorded climate normals put the comfortable, full-water window at roughly May to August: serious volume still coming over the lip, dry air, mild days. That is the season most visitors are pointed toward, and for the curtain itself it is the right one. It is also the wrong one for two of the region's signature experiences. Livingstone Island - and with it Devil's Pool, the rock lip you can sit in at the very edge - is usually open only from around mid-July to early January, with the pool itself typically running from about mid-August, and the operators are explicit that the dates move with the water. The gorge's full, technical rafting season runs roughly August to December. And at genuine peak flood, somewhere between February and April, the spray off the Eastern Cataract can be so dense that the Zambian viewpoints show you weather instead of a waterfall.
So the honest trade reads like this. May and June give you the most water and the least access. September to December give you the pool, the rapids and a thinner, more legible curtain. July and August sit between the two, which is why they cost more and book out first.
Three full days is the floor for the Zambian side. Four is the answer. Five if you want Botswana, which you might.