SCript to get created day

Dear All,

First We know in service Catalog we can't create SLA base criticial like incident template, and the template have default SLA, and my template default is 2 day.

i need help a script to get CREATEDDATE, my case is :

If a request have created and after that, if user want the sla is more than 3 day, they will choose "Change SLA",i have make a pick list for that, after submit the overdue day is increase time from CREATEDDATE + 5 day, that working good. The prolem is if they change when they create the ticket and submit, we don't have a varible forCREATEDDATE,it show undefind so how can we get time as now() or something,here my script, if i use now i think it wroing the format or something to add more time, Beside that event i change the overdue it still show late,so how can i prevent that for report

var createticket=$CS.getValue("CREATEDDATE");

createticket.setDate(7);

$CS.setValue("DUEBYDATE",new Date(ngayTaoCase));

$CS.setValue("ServiceReq_1801_UDF_CHAR8","ChangeSLA");

alert("Successful ");

Thanks Alot