For a new hire, I think all three bases (Den, Mco, Ord) are easily attainable. Likely you could get Denver immediately, but each month they might have different needs. I think everyone gets their base of choice by the second vacancy, so maybe 1 or 2 months. I think lately a lot of new hires have been assigned Denver, and guys who wanted the other bases had to wait a month. Also, remember you are considered Denver based during training, so no hotel during ground school. Seniority is based on age