never done it with brown sugar but I have done it using other retarders. MOst old fashioned cement retarders are sugar based - usually based on plant sugars and wood resins. They are a bit more advanced and synthetic these days cos chopping down all the trees to stop consrete going off too quickly was considered not a great idea.
I guess with the brown sughar you would sprinkle it on and trowel it in then wash it off the following day like we currently do with exposed aggregate concrete driveways. Refined (white) sugar would do the same thing but would probably have a much deeper effect.
Never come acroos the table salt idea though. Will probably have to mix some up and try it now.........