Hi Siga.
Your quant and verbal prep will take care of most of what you need for IR. So, you may not need to do much more for IR in order be ready achieve your IR score goal. At the same time, there are some skills unique to IR that you'll need. So, it makes sense to spend some time doing IR practice questions to become comfortable using the table sorting functionality, reading the graphs, and doing the other things necessary for correctly answering IR questions. This practice could take anywhere from a few days to a couple weeks.
For some more insights into how to prepare for IR, see this post.
Mastering Integrated Reasoning on the GMATRegarding the AWA, many people spend just a few hours preparing for the AWA, though if your English writing skills are not particularly strong, then it may make sense for you to work on your essay writing skills over the course of a week or two. To prepare for the AWA, you can find an essay template and write a couple practice essays in accordance with the template.
For more on how to prepare for the AWA, see this post.
GMAT AWA Writing Tips: 5 Steps for a 5.0+ Score _________________