You Can't Ice Skate On Frozen Jello

It's just not feasible from a logistics stand point. Taking into account the poor strength to weight ratio of your average piece of jello, even frozen, you would need upwards of 550,500 acre feet of frozen jello (based upon an average sized circular pond with a mean depth of 4')

Seriously, even if you were in Alaska in the early winter and found a pond that hadn't frozen over yet, and had the means to procure however much jello mix it would take to use the nighttime drop in temperature to freeze the mixture, it would still require very wide blades on the skates (in which case you are probably now simply skiing) or a very, very light skater.