Started time

Started time is the time where a ticket status is changed from new to something else, right?
So i have a scrip, which that when someboy corresponds the status is changed to open.
When i take a ticket, respond to a ticket the status is changed from new to open,
but the started time is not changed, how can I modify the code that also changes done by RT_System in scrips change the started time?

Thanks for any response.