Thank you for asking your important question here on Education.com
First, your child, regardless of age, should be involved with school if s(he) has been identified as hearing impaired, with OCD and behavioral difficulties. So, my first advice to you would be to contact your public school, show them all the medical and other professional reports that indicates your child's conditions, and ask for a special education team meeting. (Special education covers a wide range of services from a child needing speech therapy to much more involved services. Special educators also help to develop behavioral plans to reduce aggression as well as monitor a child's progress within the classroom setting.)
Also, I suggest to parents that they ask for a review of records meeting with the intent that a school multidisciplinarly team will review all records and determine if school based evaluations are necessary for your child. These evaluations are to decide the strengths and weaknesses of your child in a multitude of areas.
By pin pointing better your child's abilities then a program may be created which would be geared to help promote success rather than failure. Also, if your child needs additional academic support then this can be discussed, a plan may be written and all will discuss the implementation.
Keep in mind that you are an integral member of the multidisciplainary team and your information will be of much value.
In short, your child does not need to wait to start school. Public schools will welcome your child at anytime if there are special education needs. Please call your child's local school. If you don't know which school that would be our website has a tab on the homepage for SCHOOL FINDER.