As these guys have said, it really seems to vary person to person. I'm about 2 months out from FUE and the donor area has practically completely healed. I still get a pimple/bump or two from time to time, but it's not bad. The recipient area, however, is still a bit red. Of course, I notice the redness much more than anyone else does. Even my friends who know I had the transplant tell me the redness is barely noticeable in the front, and even then, only when I point it out. It was around the 6 week mark that the redness reduced enough for me to go out without a hat without being afraid people would notice.
Also, make sure you keep your scalp clean. That will help with the redness/pimples for sure. After wearing a hat, exercising, etc. make sure to shower/wash your scalp as soon as possible. I noticed if I went to the gym and waited a few hours after to shower, that's when the redness/pimples would get worse. Just an FYI.