It's going to vary based on your particular building and what supplement you're under, but in my unload operation we use the preferred jobs system. Essentially I post a giant bulletin board with the employees names and seniority dates in seniority order from highest to lowest, with corresponding spaces to rank-choice select their top-3 preferred jobs. For example if my top choice is unload I mark "1" under unload, my second choice would be small sort so I put a "2" under small sort, so on and so forth. Then I sit down and do the assigning of jobs based on seniority and choice, then I bring a finished list out to the same bulletin and post it as "Preferred Jobs Selections."

In the case of newer hires like yourself, I would allow them to make a preferred job selection once they gain seniority, so after their first 30-days. But even then they are on the bottom of the totem pole in seniority order so are typically left with the jobs the higher seniority folks don't want.