Leap second addition in linux - how to make sure kernel detects it correctly

For the upcoming leap second addition on June 30 I have been working on making sure the Red Hat Linux detects the time smoothly. I have installed the updated tzdata and ntpd package on all RHEL5 and RHEL6 Servers. I have then ran the leap second detector script -- > https://access.redhat.com/labsinfo/leapsecond

The script checks for the kernel and tzdata version which looks okay after I have updated them on server.

All the servers are running NTP and NTP Server is not managed by me so I am wondering if whatever I have done so far is enough to get past this leap second addition or do I have to notify the NTP Server admin to do some changes on their side as well ?

Also I see that there are few tweaks Red Hat recommends for servers not running NTP

such as copy the appropriate zoneinfo file from /usr/share/zoneinfo/right directory to /etc/localtime

and I also read some recommendation such as adding -x in /etc/sysconfig/ntpd in NTPD_OPTIONS

So my question is this - do I have to add the -x option and update the zoneinfo prior to June 30 event or once the leap second has been added to the clocks around the world.

Thanks.