If you don't know the temperature of your freezer, it wouldn't hurt to leave them overnight. Try making thin ice cubes and pouring room temperature water over them, to get a reality check on how quickly thinner ice melts, compared to a thicker block. Mine are the same color, but the bottoms (compared to the picture) are improved to reduce the "heat pipe" effect from the counter (bottom is slotted with raised center). Things that increase heat transferred to the ice shot glass: warmer home, higher humidity, quarried or concrete counters, and touching them. When setting up: be prepare to "fill and spill" to get a nice high rim, have a level and area prepared in the freezer ahead of time. They are less mess and more fun to use if you prepare to: have a towel at the ready, use quick warm water to run over the plastic bottoms, drink fairly soon after filling with alcohol, and recycle as an ice-cube/shot-measure for a mixed drink right after.So these do work. I did not have any problems getting the completed glass out of the mold. The only complaint I have is that there are no clear filling measurements. That's not the end of the world.They are good but being in hard plastic the also break easily when you try to get the ice out.