While answering this question I remember my JEE days, I still remember my very first day at kota - I called one of my relatives and asked him that Is vibrant study material sufficient for IIT-JEE . I just called him because he has cracked IIT- JEE with a rank of around 400 from vibrant academy 2 years prior. He suggested me that just go with the study material provided by the institute,it is more than sufficient.

Now, coming to my personal experience study material provided by any institute( may it be FIITJEE, VIBRANT,BANSAL,etc ) is designed to cover all the topics that are mandatory for the JEE and also to provide sufficient practice in order to make the aspirants profound in the concepts. So, you should just go with the study material and after covering all your homework(probably toughest task to accomplish) you can look up for reference material(books and all) .

But my observation is that in order to practice from the different books most of the students generally skip their study material and consequently they just hold the command in very few concepts that is just not sufficient to crack IIT-JEE.

So, according to me your top priority should be to finish the homework assigned by the institute and after that if you have time then go for books .