Actually, as far as the ICG (International Costumers Guild) goes, many of their members consider "Masters" division to be a misnomer. It's actually more of an "Open Division"; being in it does not mean anyone is a "Master" (and what the heck defines a "Master", anyway?), it means your skill level is such that you can fairly compete against anyone in an open competition, even if you have perhaps not been costuming very long.
"Novice" and "Journeyman" categories are supposed to be there to provide a certain amount of protection for relative newbies (developing their skills) from having to compete against more experienced and/or more technically skilled costumers, particularly to give them encouragement to continue with costuming. If one is a newbie but very technically skilled, one should in theory advance to Open Division AKA "Masters" very quickly, because that's where one's skills belong.
The International Costumers Guild Masquerade guidelines (http://www.costume.org/documents/guidelines.html
) spell it out better than I can say here. These ARE supposed to be guidelines, not hard-and-fast rules, and subject to the interpretation of Masquerade directors. However, Masquerades which follow these guidelines do usually tend to end up with enough similarity to each other to make it less confusing to the participants.
How one advances is NOT set in stone, but often it's the "Best (workmanship or presentation) In (skill category)" that counts toward "moving up". Also someone competing at a "Journeyman" level at a smaller competition might still be able to enter at "Novice" at a large world-class competition where the average skill level may be much higher.