How to prepare for the school programming olympiad in half a year almost from scratch?

Question

Java

Need help. I am turning to you with this question, because I did not really find an answer to my question from other sources on this topic and I am afraid to make a mistake due to a possible irrational choice of the material being studied. I myself am a student of the 10th grade of a general education school with a general curriculum (there is no profile with mathematics)
My level of school knowledge:
I evaluate my knowledge in mathematics at a minimum: I study at 4, I understand all the main topics, but at the same time the class is non-core (there are none) .
I rate my programming knowledge as average: I know Java and the basics of OOP, I am familiar with Android (I study additionally at the Samsung IT school where I take this knowledge) and of course I know Pascal.
I plan to write in Java. It would be best to reach a truly serious level of Olympiad programming in a given period of time. At worst, I would like to develop my mathematical apparatus and increase my knowledge of mathematics if nothing really comes of it.
Need your practical advice on a given plan:
1) How to study mathematics on your own from basic to advanced? (which books, learning sites or other sources to use)
2) What books on algorithms can you recommend that can be useful in school Olympiads?
3) What else do you need to learn in Java programming besides basic syntax, constructs and operators? (again, which books, tutorials, or other sources to use)
4) How many hours per day / week do you need to master such a program?
5) What success can be achieved according to this plan and in what Olympiads?
/* It is desirable that all educational materials more or less harmoniously combine and complement each other. */
I would be grateful for your recommendation

Answer 1

Register on codeforces.ru and go ahead.

Answer 2

An excellent resource with tasks - here you can see some topics / categories, something to learn, etc.

Answer 3

>> 2) What books on algorithms can you recommend
"Groaming Algorithms" https://www.ozon.ru/context/detail/id/139296295/
SICP https://habr.com/post/103322/
Knuth.
>> 3) What you need to learn more in programming
English. To read everything relevant, and then to look for a job for the current salary.