Energy Consumption Poll (my shop)

I have a 24x30x11 detached shop with a heat pump with A/C unit running on a 30 amp power supply. This link is the one I have.

http://www.shophmac.com/ge-az61h15dab.html

I'm not in the shop all of the time of course but I do keep my dog in there during the day when the outside temperature gets above 90 degrees. What question is should I shut down the A/C when I don't need to keep my dog in there during the day (when temps drop down in the 80s) or leave it running?

For instance it cooled down some last week do I put my dog back in his kennel. Now yesterday I did some work in there so I turned the A/C back on. I usually keep it set on 70 degrees so the A/C compressor stayed on a good bit to get the temp down to 70 degrees. It was 77 when I went in there that morning so I left the unit on knowing it was going to get hot later on in the day.

I have never had a shop with A/C or heat so I don't want a staggering power bill that I have to pay. I noticed my power bill went up some because I have been using the A/C a little this year but in the last month it has been on just about all the time. My thinking is to leave it on so it doesn't have to "catch up" when I turn it back on after I have turned it off for a couple of days. This uses more energy to have to "catch up" instead of leaving it on. I mean I leave my house on 69 degrees all of the time because that's where I am at most of the time. My mom suggests I cut it off and when I know that I will be in the shop awhile that day I should cut it on. However I sometimes don't know if I'm going to be in there for a little while or a long time. I don't want to have to go in there and cut the air on and burn up until it cools off. The shop however doesn't get that hot because I insulated it fully to the max. lol

Your input would be nice to hear.