you could just compete at the level you think your skills are at. if you are costuming at a master level, even if it's your first time, there is nothing to stop you from entering that category. not telling your group member what level you're entering at seems silly to me. If their costume is the same quality as the rest of the group they should have no problem entering as a journeyman too and should feel they deserve to be there. delaying moving up to the next level seems like you're trying to keep an unfair advantage over others.