I manage a "Green cleaners" and it's recommended to immediately "water down" the aforementioned stains with H2O as soon as the stain appears-even if you are out at a restaurant and won't be leaving for a couple of hours.
The reason? The LONGER the stain stays in your clothing (while waiting to take to a dry cleaners, wet cleaners, etc, if that the "sugar" enzymes in certain stains will start breaking down the fabric itself, and particularly on rayons, silks, and even cotton -waiting a week to have it "professionally spotted" will do no good.
Just Dabbing the stain with your napkin in a glass of water will "dilute" the sugars and will save your clothes.
Hope this helps, Maggiem Austin
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