Hey aspirant,if you ask me I'll suggest you to go  for Yellow book of vajiram and Ravi this year with pt365 of vision ias. If you can then just revise the past 7–8 month current affairs in s&t in detail. It will be sufficient.

Hope it will help you

NCERTs are the basic. You should be thorough with Class 6th to 10th Science, 11th and 12th Chemistry last two chapters, Biology class 12th last two chapters.

If you have gone through all this try TMH Science and Technology manual and solve previous years question papers. If you find something that you have not gone through, simply browse the topics and take notes for it. To be updated with current science and technology selectively read Science Reporter. This is enough to cover all the aspects of Science and Technology for UPSC.

All the best