The time you worked in '06 was kind of like a dress rehearsal for the real thing. No seniority gained. Your '07 hire date becomes your seniority date once you work the required number of days to become a permanent employee, so you have 19 months roughly. When they post a bid sheet for cover or full time anyone wanting to move up signs the sheet. The person/s with the highest seniority win the position/s. The only way your position is improved is by people moving out of the line above you, either by going to another job classification or by leaving the company. Seniority sucks when you are on the bottom of the totem pole, but it's great when you are on the top.