Once they sink, they are wet, plant them. I use the paper towel + jar method myself, I plant when the ends have a "white head", before they shoot out a tap, if I catch them before that at least.
I put mine just barely under the soil "white head down" (beginning of taproot beginning to come out) and I spray the area they are in every couple hours with plain water.
You can go ahead and plant them, about a centimeter or even less is fine, just keep the area moist without making it compact itself, and they should pop out in no time if all goes as it should =)