Hello aspirant. 30 days, if you plan the time perfectly,It would give you the better preperation. So the major topics for the exam would be

1.Verbal ability and reading comprehension

Hope you know the topics under these. So I am not going deep into it. Give a bare minimum of 2.5 to 3 hours per day for this. Take a topic, have the basics at finger tips , practice bits from multiple sources every day. This won't take that much time and eventually you will get used to it

2. Data interpretation and logical reasoning

Some of the important topics like blood relations, series needs daily time. Apart from that spare a minimum of 1.5 to 2 hours per day on this. Not much Is required because pie charts, data interpretation and all depends on how different you think. Doesn't require much of a practice

3.quants

Most important part of the exam. Each topic is really important. Spare a bare minimum of 4 hours per day on this. Make a notes of all formulae and the key points for each topic. Practice each topic and make it perfect.

Plan your time accordingly and you will definitely ace your exam

All the best

Regards

Nikhitha