Then how long before I starts to consider me as not a threat?
If you forget your girlfriend's birthday how long until she forgives you? Could be that she doesn't care, could be that she'll never talk to you again, could be anything in between. Depends on the person and how you deal with it, and different girls will respond better to different strategies. Telling some to get over it will work, with others it'll make things worse. Giving some flowers will work, others will see it as an empty gesture and be resentful.
Snakes are individuals too. Some hatch out with no innate fear, others will always be fearful. Some will respond well to not being handled and just seeing you, others will be at peace after time with zero impact from you, others will respond to being handled, and some will respond badly to one or more of these. The way you handle is as important as whether or not you handle. The typical advice given to newbies is to persist with gentle handling. This sometimes works, sometimes doesn't. Snakes tend to calm down over time with or without handling. Whether babies hatched in captivity or wild caught adults, a period of time without anything actively trying to kill them generally makes a snake feel more at peace. Generally, if handling freaks a snake out, handling it more is counterproductive. Sometimes a talented handler can calm a snake but a poor handler will freak the same snake out. Some people are instinctively good at handling snakes, some learn over time, some never learn.
If you now feel confused you are likely understanding why the typical advice is so simple; most people can't be bothered explaining and/or couldn't understand the situation if they tried.
If you want a pet which quickly learns to love you, is active and fun to watch as it displays antics, is interactive and actively seeks to physically play with you, rats, dogs and ferrets are great pets. Snakes are absolutely brilliant pets, I've kept and bred many different animals from fish to cats to birds to ferrets to rabbits to various invertebrates to several others and snakes are probably my favourite animal to work with, but you need to appreciate them for what they are and not expect them to do what they don't.
