Tips on tracking Call Handle Time using Excel

At my new job the CHT/CRT that we receive is three days behind what we are actually using. It makes it hard for me to keep track of my talk time, so I thought I'd use excel to track it. I can see the time I have been on each call through the day. Any tips would be helpful. Today I figured out that I had to put it in 0:0:0 format to get it to average correctly. (I was trying to get it down to just seconds but that seems a bit complicated. I just then used "average=(a1:a30)" to average them together and it seemed to work a bit.

I appreciate your help!

PS: it's a vmware/citrix program that i'm running excel through so i can't save it and will have to set it up daily.

Any Help at all?