Start smaller than feels reasonable. Do not try to talk to the camera on day one. Begin with formats where you barely appear, like voiceovers over your work, then add one line at a time. The fear fades with reps, not with willpower, and the boring editing is what stops most people, not the talking.
Completely normal. Expertise and camera comfort are unrelated skills. Disliking the camera has nothing to do with how good you are at your job; it is about being watched, which almost everyone finds unnatural at first. It fades with practice, and it is not a sign you should stay off video.
Through a gradual ramp, reps, and real-time direction, not a single brave attempt. Start with low-exposure formats, record in short takes you can redo, get a second pair of eyes on lighting and delivery, and build a routine so filming becomes ordinary instead of an event.
For most people, a few weeks to a few months of regular practice, not years. With a gradual ramp and consistent reps, the camera usually stops feeling strange within about three months. The timeline depends far more on consistency and starting small than on natural talent.
Stop reading and start explaining. Know your points, not your exact words, talk to one person instead of an audience, and do several relaxed takes. Stiffness comes from trying to recite a script perfectly; naturalness comes from speaking the way you already do in the room.