There’s no definite answer to be very frank. It all depends upon how good are you at your fundamentals.

It’s equally important to decide upon which field you have to go in depth. Covering all the thing is quite challenging, if you’re good at the fundamentals & have decent domain background, it should help a lot.

Ideally spending 15hrs per week may get you to some level after 4–6 months is the least, but this is not scientific, people have done in very less time too. It’s a generic observation & what I have heard from experienced people & various videos.