Answer: So if you're around somebody who has the flu, and the next day you feel pretty good, you're not out of the woods yet. You can actually develop symptoms up to four to five days after being exposed to somebody who has the flu.nswer: So if you're around somebody who has the flu, and the next day you feel pretty good, you're not out of the woods yet. You can actually develop symptoms up to four to five days after being exposed to somebody who has the flu.