Make sure you have big and small pieces of plaster bandages, use the small ones on and under the nose.
I used 2 or 3 packages of plaster bandages. 1 is not enough and each package was 2 meters.
This time wait for 10 to 15 minutes. You have to be sure that the bandages are hard enough to hold the alginate. Cause you are going to pour plaster in it afterwards and if the plaster bandages are thin or are not hard enough all your work will get wasted.