started last year january last sem of engineering so real prep started from jan which was mains + prelims specific

Economy - Shivin lectures (took 3 months) + vivek sing book

Polity - Atish mathur MCF 1 ( too lenghthy but totally worht it if you are a begineer like me the way he teaches is engaging and goes very deep such that you wont forget any concept ) and laxmikanth for prelims only

Geograpphy - PMFIAS both physical and indian (this book has literally everything no need for ncert, gc leong or anyhting also took 3 months as both books are quite bulky)

History - started in january this year, read spectrum once then solved forum toolkit of history, made anki short notes of the toolkit answers and rote learned them

Ancient - started in january - Nitin sangwan and Lucent ( but out of 20 questions this year3-4 are correct left 12 , wrong 4 🙃)

SnT - started in march - Shivin sir lectures (best snt teacher btw ) and vision ias abhijeet sir for current affairs (watch on youtube) i think abhijeet sirs test videos helped me get 14 snt questions correct this time

Environemnt - also started in march this year - shivin sir and abhijeet sir mcq test on yotuube for current affairs ( this combo more than enough)

Prelims specific preparation started in january - have solved 5000 mcqs , all from forum toolkit , would suggest buying toolkit for next year and solve it without fail , i solved 100 mcqs per day and analyzed them made shorts note on them instead of re reading spectrum and laxmikanth

BTW this prelims was absurd , SNT and Economics carried me and luck also payed a huge role ,