The proper procedure is that you file Interim Application for Access. Request the judge to send you and your wife for mediation on access to child. Arrive at at a mutal consent for spending time with the child. The Mediator will help you arriving at consent. The consent terms will be certified by the Judge and you can avail the access as per these consent terms.
Don't Push for your custody case very aggressivly. If yoy do so your estranged wife will create hinderance in access. Hence the best thing is that try for access and push for a Joint Parenting Plan.
Show your willingness to maintain the child. Agree for Payment of his school fees and other genuine expenses.
There is a lot of tutoring of the child in such cases. Engage a good Lawyer
Wish you all the best.