No, you can't board early on JetBlue flights if you're a military veteran. Early boarding on JetBlue flights is reserved for people with disabilities, frequent flyers with a high status level, active military members, and people with small kids.
However, if you're enrolled in the "Veterans Advantage" program, you are eligible for two different perks when flying with JetBlue:
5% discount on the base fare for all JetBlue flights.
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