30% glycolic acid peel at home mild burning...when will it begin to work?

You do not mention the pH, brand, or other active ingredients, if any.  In my office, I apply 70% glycolic acid with strontium nitrate at a very low pH.  The strontium nitrate suppresses side effects such as stinging, redness, and blistering, while allowing the high concentration of AGA to create maximal exfoliation and stimulation of fibroblasts over the ensuing days and months.  I do not use any peels with concentrations lower than 70%, as I have not seen significant benefits.I doubt that a 30% glycolic acid peel left on for a few minutes is going to have much of an effect. Whatever benefit you see in terms of exfoliation should be seen within 24 hours; stimulation of fibroblasts can result in increased protein production, which would not be appreciated for at least one month.