Haven't really tried freezing smoothies, but I reckon if you make some in advance, you can pour them into those resealable food-grade freezer bags, then blend again with some milk or fruit juice.. Alternatively, try freezing them into ice sube trays. Just don't use bananas as they turn brown when oxidized..
..but what I normally do to ease preparation is to cube different fresh fruits, pack them into serving size portions and freeze them -- strawberries, bananas, mangoes, peach..You can mix and match fruits or a single variety per pack.
Granulated sugar doesn't "melt" as fast so best to use (simple) sugar syrup or honey to sweeten. I use flavored yoghurt if skim milk is not avail, plus some cube ice with the fruits