From the information you have provided, you should not worry about filing for custody at the present time. If dad wants to see his child, he should be the one filing for visitation. It would be his move to take action, not yours. So long as he has the child's contact information, you are not required to take any further steps. Having a custody order in place can restrict your movement should you later decide to relocate as it could mean getting the court's permission instead of your own freedom to move.
If the goal is to get child support, then you can file for that through the child support agency in Hawaii. Since you are the current parent who has primary custody of the child, you can get support even if there is no custody order on record.
Further when it comes to infants, a parenting plan with an infant is usually one or two times a month weekend visitation at the mom's place of residence, since the goal is to not disrupt the child's stability which is important while they are infants. But as already stated, you should not worry about doing this, it should be the father's job to ask for visitation, not yours. If you want child support, contact the Hawaii child support agency to assist you in setting that up.
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