How to use dynamic value for start_in using environment variable in gitlab pipeline child job

Question

I need to start child gitlab pipeline job using environment variable. I tried below but getting error as jobs:job2 start in should be a duration.

variables: DYNAMIC_START_IN: "1 minute" # Set your dynamic start time here.

job1: script: - echo "Starting job in $DYNAMIC_START_IN" start_in: $DYNAMIC_START_IN

I tried sending in environment variable and was expecting variable value sent to delay child pipeline job. However, getting error as jobs:job2 start in should be a duration