This is a very important distinction that is more in play now that new hires have been getting WB awards. Normally on NB fleets you can hold your plane in any base well before a year. However, a NYC 330B may not be able to hold ATL 330B after 12 months, but that pilot can break their new hire lock after 12 months and be awarded any other fleet in ATL they can hold. Just note that whatever NH lock that is left will be added on to the new 24 month lock for changing fleets.