How do i know if ProxySG is in synced with the NTP server ? It seems nothing happen when i click "Acquire UTC time"

When "acquire UTC time" is clicked, you will find this in the packet capture
- in NTP client request packet, origin time stamp = APR 11, 2016 01:10:00 UTC
- In NTP server response packet
i) origin time stamp = APR 11, 2016 01:10:00 UTC
ii) Receive Timestamp = Apr 11, 2016 02:13:02.662416000 UTC
iii) transmit timestamp = Apr 11, 2016 02:13:02.662448000 UTC

According to the RFC

Receive Timestamp
-------------------------
This is a 64-bit timestamp established by the server host and
specifying the local time at which the request arrived from the
client host. If no request has ever arrived from the client the
value is zero.

Transmit Timestamp
---------------------------
This is a 64-bit timestamp established by the server host and
specifying the local time at which the reply departed for the
client host. If no request has ever arrived from the client the
value is zero.

Originate Timestamp
----------------------------
This is a 64-bit timestamp established by the client host and
specifying the local time at which the request departed for the
service host.  It will always have a nonzero value.

The difference between origin time stamp and the transmit time stamp is about 3780s ( 63 minutes)

In the event log, you will find this

"2016-04-11 09:10:01+08:00SGT "NTP: Queried server ntp2.bluecoat.com per user request, system clock is 3781 seconds 619 ms slow compared to NTP time. Updated system clock." 0 90000:1 ntp.cpp:819"

It shows that ProxySG is in synced with the NTP server, you need to re-login to see the effect.