There aren't a lot of great breakfast options at Universal, so we usually end up at Voodoo. We've grabbed some in the morning, then ate them while waiting for Early Park Entry rope drop. We've also held on to them until we got in the parks, then found a place to sit and eat them.
The past 2 or 3 trips, on our first night, we've gone and picked up enough for the other mornings of our trip. They save pretty well in the room for 2 or 3 days.
As stated above, they are very busy at night because a lot of people have this same idea. On our trip this past October, they were out of a lot of flavors at the end of the night. I went through 4 or 5 choices before the cashier said they had it, then when they were packing the box, they called me over and said they didn't have that flavor either. I picked another flavor and they threw in an extra one of those for free.
For what they are, I think they are a bit over priced... but are still a cheap breakfast.