CAT

Yes, you can. It would help you in a huge way if you are going to do MBA for sure once you are done with your graduation. You can apply for some coaching class for mock tests. Mock tests would help you in preparation. Or if you want you can join the classes as well. Many classes nowadays provide feature like if you are not able to get into the college that you want you can sit for their lectures in next year again. You get access to their online study material as well. As you would give the CAT exam while you are in the final year of your graduation you will get an idea about how entrance exams are in nature. Thus, even if you are not able to score in this year you stand a pretty good chance in the following year for scoring more marks as your score will improve only. So you should go for it in your final year of graduation. There is a lot free study material as well as free mock tests available online which might be useful for the preparation.

I would list out the pros and cons of various reputed and best performing online coaching institutes which would lead you to pick the best from your side.
1) Mindworkz - Best CAT prep institute in India
You would have the privilege to grab the knowledge of most recognized and reputed trainers but it is expensive.
2) Career Launcher - Coaching for CAT
Offers large amount of practice questions.
Videos are really good and understandable.
No live sessions to get your doubts clarified.
Expense would be a burden again
3) Olive Board- Online Practice & Preparation Platform
Offers mock tests series and unlimited Online Tests with 10,000+ Questions and Detailed Solutions.
4) Handa Ka Funda - Online CAT Coaching Classes - MBA 2017
750+ video tutorials
Live classes every weekend to get your doubts clarified through live chats
CAT 2017 Test Series along with solutions.
Economical
22+ Theory Books for preparation
The above mentioned players are reputed and well recognized institutes. There are a lot more players in the CAT coaching market. All the institutes mentioned above hold success and failure stories. It is up to you to pick the one of your choice.

Top Coaching Institutes In Allahabad are,
1) Career Forum
Address Of Institute:
43/4 S.P Marg, Opposite HDFC Bank, Civil Lines,
Allahabad, Uttar Pradesh.
Some Course fees of Career Forum (In Rs.)
CAT Premium- 11900
CAT Plus- 10700
Focus CAT- 7900
2) TIME Institute
Address of Institute:
14/2 A, kamala Nehru Road, Infront of Prayag Sangeet
Samiti, Besides of Civil Lines, Hanuman mandir, Civil
Lines, Allahabad, Uttar Pradesh.
3) Career Launcher
Address Of Institute:
43/33, sardar Patel Marg, Ground Floor, Civil Lines,
Allahabad, Uttar Pradesh.
4) IMS
Address of Institute:
2nd Floor, 54 Shri Ram Complex, Sardar Patel Marg,
Civil Lines, Allahabad, Uttar Pradesh.
5) Lakshya Career Institutes
Address Of Institute:
649, Old Katra, near Mishra PPharmacy, University
Chauraha, Allahabad, Uttar Pradesh.
6) Panacea CareeAddress Of Institute:
33/43, SP Marg, Civil Lines
Allahabad, Uttar Pradesh.

If you are preparing for CAT exam then you don't need to prepare separately for IBSAT exam. The reason behind this is the topics which are asked in CAT exam are the same topics that are asked in IBSAT exam. So, both exams are almost same but the thing differs is difficulty level. CAT is tougher as compared to IBSAT. So, try to prepare for CAT exam because this can help you score good marks in IBSAT.
IBSAT exam includes Reading Comprehension, Verbal Ability (VA), Quantitative Aptitude (QA) and Data Interpretation (DA). Whereas, CAT exam includes Verbal Ability (VA), Reading Comprehension (RC), Data Interpretation (DI), Logical Reasoning (LR) and Quantitative Aptitude (QA).
So, both the exams are having similar content. Preparing for CAT exam can cover the IBSAT exam syllabus too and this can help a candidate in every aspect.

Here are my top few suggestions:
1) Learn tables till 20.
2) Learn the values of fractions like 1/1 = 1, 1/2 = 0.5, 1/3 = 0.33 and so on till 1/30. I have learnt the shortcut for memorizing this when I was preparing for CAT. You can find it somewhere on the internet. But learn it.
3) Learn the square of numbers till 30.
4) Learn cubes of numbers till 20.
5) Learn to visualize fractions as pies (pie-charts) and then apply calculations like addition/subtractions to it.
7) Learn more Pythagorean triplets like-3,4,5 - 5,12,13 - 8,15,17 and their multiples. You must be able to identify these triplets in problems. There will always be at least one problem on triplets.
8) Learn trigonometric ratios for popular right angles triangles like-45-90-45 and 30-60-90.
9) Finally, practice a lot.
Also, remember to keep your eyes open and be alert. Did you notice that I skipped point 6?
All the best.
P.S. I got 96-97 percentile in Maths Quant for 2 consecutive years.

A job with studies becomes a hectic task. But there are many people who do both at the same time.
Firstly, you need to plan and organize your activities. Like the time remaining after work hours, effective utilization of this time is needed.
Also, time spent in traveling should be utilized.
Start reading a newspaper like The Hindu, Editorial section to improve in verbal section.
Also, keep formula's /basic concepts ready on cards. So that you could read these cards during breakfast or idle time.
Also during lunch break or so see, News channels.
Things will become easy once you are sorted with the correct utilization of available time. CAT requires hard work, and there is no exception to this hard work. Eventually, these efforts will sail you through exams and make life better once you get a good college.
Also "Change of subject is rest to mind", so keep doing different subjects (Maths, LR, Verbal) inrotation.
Sometimes when tired, watch an English movie (will improve verbal).
This helps you keep work-life balance and prepare you for MBA.
All the best.