I sometimes ask the same question. But probably we cannot find out about a new bounty immediately after its publication. Even websites like Bountiesalert.com or Bountyhive.io can't do that, either. Anyway, let's hope someone figure out the way and share with us.
No need to worry it's not about early bird as long as you are qualified on the bounty you can participate, some of the bounty campaign I've participated in are I'm a late comer but nevertheless I still made a good profit, its better be late but you are on right project than an early bird with a wrong ICO.