How many days does it take for anemia symptoms to disappear after iron supplementation?

See below. It depends on how anemic one is. Symptoms should resolve within 3-6 weeks if low iron is the cause of the anemia, and the iron is being taken properly and is being absorbed.
Months. Usually it may take a few months for all anemia symptoms to completely disappear after oral iron therapy, with intravenous iron therapy symptoms are resolved faster in 1-2 months.