Set timer even for process started by startProcess()

Hi everyone, 

I have an interface that contain a submit button to submit a request, that when the submit button is clicked, it will start a process model by a!startProcess() in a!save().

After clicking the submit button, I want that process model to not run until 21:00 that day. How do I set the timer event to achieve that result? The button will be clicked every day, and I want to delay that day's process instances until 21:00 each day, not just 1 single day. I'm not sure how to define the date and time yet. Could any one help?

Thank you!