Realistically, quarantine can be as strict or as relaxed as you feel is safe. Honestly, your birds will be exposed to each other on some level without severe safety precautions. Airborne/aerosolized liquid when the bird sneezes, feather dander going through the air, germs on you and your clothing and many other factors are impossible to control. Some level of quarantine is always a good idea, however I think it should be varied depending on the bird's past and the likelihood of disease transmission.
That said, when I bring a new bird home, they do not make contact with my original birds for at least two weeks. I use F10 to sterilize play stands in between old and new birds, and I do not share anything between cages unless it is cleaned first. I also wash hands between birds at this point. Unless I am nervous about the bird's health status, I do not worry about keeping the bird in a different room, changing clothes or anything drastic like that. For me, with parrots it is a balancing act between getting the new bird comfortable and involved and keeping your original birds safe.