early-bird
adjective [ before noun ]
ukusavailable early in the day:
They rose at 4 a.m. Tuesday to catch an early-bird flight to San Francisco.
early-bird special/discount/rate The store's early-bird special was 50% off everything until 11 a.m.
used to describe a person who does something early in the day, especially in order to get an advantage such as a cheaper price:
early-bird investor/shopper