Need to configure timer to execute on specific date and time in Start Event node of Process Model

Question

Hi All, 
 I am having requirement to configure timer in Start Event node of process model. I want this timer to execute on specific 'date and time'. This date and time is coming as an output of one expression rule which is returning 'date and time' datatype output. 
 Output of Expression Rule: 7/26/2025 12:00 AM GMT+00:00 
 
 Please help me at what all places what all things I have to configure to run process model once on this day at that specific time

Stefan Helzle · Answer

Running an expression inside a start node timer will not work. It evaluates that expression only once an the time of publish or deployment. 
 If you have to use this expression, start the process in a 10 minutes interval, and evaluate the current time against the expression output in an XOR. Then, either continue the process, or go to an end node.

Shubham Aware · Answer

Timer expressions are evaluated at specific intervals, not dynamically during runtime. The solution is to configure a periodic timer that triggers at regular intervals, then immediately add an XOR Gateway with the condition now() >= rule!YourExpressionRule(). When the condition matches, proceed with your workflow; otherwise, terminate the instance at an End node. This creates a polling mechanism that monitors at each interval until your specified datetime arrives. 
 Remember to set the process model to Inactive after your target datetime to stop recurring.