Hi Bhavya, 

        Start off with reading NCERT books for PCB. For biology please focus on the diagrams, the most crucial sections are : 

1)Human physiology

2) Genetics

3) Biotechnology

4) Plant Morphology

1 month is not going to be enough to tackle all 4 subjects, so please study before time. You have 9 months, that's more then enough to clear your concepts of PCB if you use your time wisely.

Do not leave NCRT books, there are many questions based on diagrams fom Biology sections that are taken straight out of NCRT books. Study them please. 

As per outside resources, if you think you have covered your syllabus well before time go for a crash course 4 months before the exam to refresh your concepts one more time. 

Practice daily and for AIIMS I would stronlgy recommend you to purchase practice papers of previous years. Happy studying !

Hope this helps!

All the best :)