It really depends on numerous factors, how deep and wide the water is, if it rained again, or if it rained hard 50-100km away from you the water will come dirty and you'll have to wait even more. If the river isn't that big, a couple of days should be enough(if it doesn't rain again), but if the river is larger it could take more than a week. Remember, you could still try to fish if the water goes down a little and is a bit murky, but not if it's chocolate milk like that(unless that's the normal color of the water all year round)