First time posting here. I have been suggested from stackoverflow to post here. I notice some questions similar to this exist, like Can a beginner in programming start learning game development? and etc. If this question is offtopic, hopefully I can get advice on where I can post this (not sure whether I should post this on gaming SE or gamedev SE instead). I would like to ask advice on learning programming.
I have a strong desire to create a music/rhythm mobile game similar to Guitar Hero or Piano Tiles, but with some twists and flavours of my own. Here is my situation that may be considered.

I am weak in programming language. I do not know Java (where many told me this is the language to go for my purpose). I mean, I have been introduced to some basics of Pascal, C, C++, or done some coding with Matlab, in high school or undergraduate study, but never have I learnt or truly dedicated myself in programming.

Part of the reason is because I focused a lot on mathematics (bachelor and master degree). My bachelor thesis used some coding in Matlab (I actually loved doing pure math but the topic really interested me, so I learnt Matlab instead), while the master one got me back to pure math in discrete math. Now, I finally have the time to do this.

Therefore, I honestly have a clear and detailed picture of the algorithm I want to create, and I can write them down too since I did that quite often in math. However, I am pretty sure the journey is still far because I eventually need to learn the language.
Here are some questions that hopefully can be addressed:
A. Considering the above, how long/how hard realistically would it be to reach the above goal, assuming 4 hours of work/learning a day? I know this is very opinionbased, but that is actually the point and hopefully it can help.
B. I wonder about this too, but do there exist any community or service that help creating a program for you upon your request? If so, how do they work? I mean like, the price, the method, etc.
I appreciate the advice a lot. Thank you in advance.
EDIT: I posted the link as an example, where I thought this would be allowed since there are some responses in that question too. Hence, I tried putting my intention in the first paragraph above too. Thanks for pointing it out.