It is very common for it to take a week, though it can happen in four days occasionally, and can take up to two weeks occasionally. You need 24 hours with AA before adjusting everything. Then the water clouds up and it is difficult to maintain an FC level for a couple of days, and then it can take a little while to get everything back to normal levels. It is also possible to get algae during the process, which adds at least another week.
Using sequestrant while you have stains has pros and cons. Sequestrant is fairly expensive, and may do nothing. On the other hand, sequestrant alone can sometimes remove the stains (not common but it does happen now and then). Plus, if there is still metal in the water sequestrant will prevent the stains from getting worse.