Generally, for a better deal it’s recommended to book in a timely manner (to save up to 24%). Cheapflights recommends you book around 90 days prior to your deserved date. Booking as early as you can also increases the likelihood that you’ll get the ideal car.
Yes, you can rent a car for a month in S. VallabhBhai Patel. Check Cheapflights for the latest prices and car type availability.