If you use a dechlorinating agent/ water conditioner that removes chlorine, then the chlorine should have come out within a few minutes of the conditioner being added to the water. However, it can take some time for the dechlorinator to come in contact with all the chlorine molecules in the water so if the water is aerated or circulated with the dechlorinator in it, then it will be more effective and the water should be safe to use within 30 minutes.
If the water is just tap water that has been left to stand without dechlorinator, then 24 hours is the minimum time you want to allow the chlorine to come out. Therefore 1.5 days should be adequate in either respect.
If you need to do lots of water changes you would be better off getting a bigger bucket (say a 45litre plastic rubbish bin from the hardware) and filling that with water. Add your conditioner and an airstone and allow it to bubble away. Then you can use it when you need it. After you use some water top it up and leave it to bubble away for another day before use.
When I had my fishroom I simply had holding tanks for water. They were bare tanks that sat on the top shelf of each stand and I would fill them with water and leave the to aerate for a few days. Then I drained out the dirty tank water and refilled the tanks with the aged/ dechlorinated water from the holding tanks.
A friend used a 200litre plastic water container for the same thing. He used a small water pump to circulate the water and to pump it up to his tanks during the water changes.
