Sounds like you’ve already made a reasonable start!
To learn about networking, the CCNA courses are good, you don’t necessarily need the exams but the content is excellent for learning about networking and routing and switching etc;
This is a free study guide site for ccna so you can learn for free;
You don’t need programming experience as such, but learning some bash scripting to be able to chain tools together, or even some python is a good start;
Then there is practicing your art of course;
How long it takes, depends on how quickly you pick things up really, and the best advice is to get to know people already involved in the field, networking people is perhaps the greatest tool you can have in this field.
After you’ve gotten good with the free stuff I’ve linked too, or feel you are ready for some certs the the best one by far would be the OSCP in terms of proving your creds;
If your looking for a junior role somewhere first, you could start with some free certs like this sort of thing, just to prove your interest to a prospective employer;
and platforms like hack the box can be used too to showcase your skills.
Happy hacking!