there is a bid out sometime after the bid closes that has all the available slots per month to the different bases. It's done by seniority order so depending upon your seniority going to your new base you might be able to pick a good time for you. For example, the last bid closed on Dec 2, 2021. I think the base transfer bid was in January . IND had two or three slots for captains every month from about April through Sep if I remember correctly