If your ERP can't connect a NTP server, you can set the date directly in the CLI with :
set date MMDDHHmmYYYY
or
date -u MMDDHHmmYYYY
where
MM : month
DD : day
HH : hour
mm : minute
YYYY: year
ex: date-u 060818452016 for 6th june 2016 18h45
Keep in mind : Edgerouter don't have an internal RTC clock which keeps real date and time. So whitout NTP synchro, when you shudown it or with a power outage, their clock gets a delay gap.