I will give it a shot at answering it. First and most important thing: stick to the 25 hours per week.
So, the milestones I see to be able to start applying for good jobs is: finish FCC Frontend Certificate and have about 5 other small projects in your portfolio with the code open at Github.
With average 36 hours/week, I took 2 months to finish FCC Frontend certificate and about one more month to finish 5 projects. I consider myself to have a good natural ability to coding.
So, with these premises, I believe in about 5 months to start applying. When you will get a job is much more unpredictable. But I can say more 3 months applying is a safe bet.
So 8 months for a junior job. This also helps you consider quitting your job to dedicate fulltime (it makes a lot of difference), with 3 big IFs: if you are really hating your job, if you are pretty sure that you would like to work as a software developer and if you can afford it.
Good luck!! Feel free to keep posting here at anytime. I will keep updating this thread with all my posts too.