Turn on the night before you leave and most will be cool and be ready to use.
Have you checked what temp it is dialed in for? It might be set at the lowest temp set. I'd check that first. They usually have a range of 1 to 9. 9 being the coldest, most keep food cold and ice frozen around the 7 number.
We must be willing to get rid of the life we've planned,
so as to have the life that is waiting for us.
"Nobody knows how we got to the top of the hill, but since we're on our way down, we might as well enjoy the ride". ("The Secret Of Life", James Taylor).
What we do is feeze a couple of water bottles and then put them in the fridge overnight and that usually helps cool it down fast. It seems to cool down faster on LP. I also have added one of those interior battery operated fans to circulate the cold air in the fridge and that made a world of difference. The one thing you shouldn't do is put warm stuff in the fridge as it just warms up the fridge so if you have your stuff pre-chilled like sodas or whatever it stays nice and cool quick.
2005 Salem
2006 Ram 1500 Quad Cab Hemi 5.7L
"If we ever forget that we're one nation under God then we will be a nation gone under." - Ronald Reagan
Mine takes about 6-12 hours to cool. I assist it by loading it with pre-cooled foods, a jug or two of frozen water. You can tell the unit is cooling when you feel heat from the back of it.
I don't bother to pre-cool the fridge - carry my food in a cooler, transfer once at the campground. I usually have ice in the freezer portion within 12 hours, and it will then be cold enough to keep ice cream frozen!
I find it cools faster on Gas then I switch to Electric if available. My Jayco takes about 4 hours when it is in the 70's. Higher takes longer. In the mountains I often have problems with it freezing items unless on the lowest setting.