It will make the ethanol solution more hydrophillic, however this will not help your extraction process. If experimentally you find it helps with your winterization process I would add the water after you extract. Only, only, if you have experiemental evidence of it aiding in the process. I would not be able to predict the outcome of this dilution and how it would affect winterization but I do not think it will help during extraction at all, if anything it will pull more unwanted water-soluable compounds. This is just my two cents and I have not experimented with this just thinking.