Customized scheduled publish event for workflow

I want to have a custom step/ dialog where the content approver can choose when the content should be published. 

This is my workflow design. The first step is dynamic participant step where the approval will be assigned to a group dynamically. The approver can either reject or accept the changes and it will immediately publish the page (the branch 2 has a process step for activate page) if the content is accepted. I want to provide option to the approver to choose when the content should be published if they want to go for publish page option (branch 2).

Is there any OOTB facilities or I will need to have some custom configurations? How do I implement them?