Proficiency is probably relative to the task/individual.

Best way to start is by starting. Set up your environment, gather resources, invest time. Download 2-3 textbooks, sample them, pick your favorite and work through it. If you get stuck, reference the topic in the other texts. You can also benefit from using YouTube or Udemy for yet another perspective on a topic. Push through.

You don't need to focus on books, but aside from learning style/preferences, they are the most complete, accurate and concise path you can take ime.

Learning pace is also relative as it is largely dependent on prior knowledge, but if I was to guesstimate, starting fresh, it would take about ~3 weeks if you binge weekends and spend 4-5 hours otherwise per week to feel capable/comfortable with the language itself.

Aka spend time learning! Good luck!