What works for me is to take a spray bottle filled with distilled water and a sponge. Put the hygrometer in there but not the humidifier.
Spray the inside of the humi so its wet but not soaking wet, if you get me. Wipe down the whole humi with the slightly damp sponge. Wet the sponge so it is wet but not soaking, put it in the humidor, suspending it above the bottom with say, popsicle sticks or something. Close the humidor and don't open for 24 hours.
After 24 hours, look at the humidity level. It should be high, say 80%. Spray the inside again, wipe down and this time don't leave the sponge in there. Wait another 24 hours.
Then put the humidifer and if it stays constant around 70%, you're golden.
I use the spray bottle so it doesn't get too wet. I'm sure other people here have some ideas.