I tumble all my brass before loading. Much easier to see defects with clean brass, plus I like shiny brass.
Generally, when I get back from the range the brass gets deprimed with a universal depriming die and then goes straight into the tumbler. I usually let it run at least 3 hours, but sometimes I forget and it'll run overnight, making it extra pretty. Once done I clean the primer pockets and make sure no media is stuck in the flash holes before I begin the loading process. If I loaded anything under .224 cal I might not tumble just because it could be really hard getting the media out of the case, but .22-250 on up I tumble everything.