If you are using the DHCP server on an SRX (and this should apply to other Juniper products running Junos) you can set up time options for DHCP clients on your network

Option 42 

Option 42 NTP server – tell the client where to check for the current time

 set access address-assignment pool OfficePool family inet dhcp-attributes option 42 ip-address 10.10.10.10

The dhcp client will check 10.10.10.10 for the current time. If you are running a Windows domain, you probably want to set this to the ip of one of the domain controllers (my first choice), or a device on your network that is a time server, or one of the many public time servers

Option 100

Option 100 provides a POSIX text string that defines the time zone offset from UTC, along with information on Daylight Saving Time. An example of this definition for the Eastern time zone in America is

set access address-assignment pool OfficePool family inet dhcp-attributes option 100 string "EST5EDT4,M3.2.0/02:00,M11.1.0/02:00"

This specifies a time zone 5 hours behind UTC (four hours during DST). DST starts at 2:00 am on the second Sunday in March and ends at 2:00 am on the first Sunday in November.

Option 101

Option 101 provides a text string that corresponds to an entry in the TZ database. An example of this type of entry for the Eastern time zone in America

set access address-assignment pool OfficePool family inet dhcp-attributes option 101 string "America/New_York"

The value entered must exactly match an entry in the TZ database, where it will be used to determine the UTC offset and DST information. The database is maintained by the Internet Assigned Numbers Authority (IANA) and can be referenced at http://www.iana.org/time-zones.

Tested on Junos 21.4R1.12