If this is not to late here is the best method.

you need hot water not so hot that you can't stick you hand in it but as warn as you can stand. Get a pan for your water then put a few drops of dish soap in. Dip your decals in the water with backing on them and then lift the backing off after you have a nice wet surface. Dip in water once more then position them on the plane as you want them displayed. Once positioned where you want them then squeegee water out.

Randy