Does not make a difference. I dissolve the ES in warm water and add cold. I prefer to drink it at least at room temperature, it goes down quicker.
Something completely different I once put my OO/GFJ in the freezer to make it cold, it was so cold that I had to drink it in stages. I won't do that again.I also use room temperature and I drink it over the sink as fast as I can to get it over with.