I'm not sure if Tiia14 is reading the posts?
My 2 cents is the battery should last a long time before it won't be able to start the car. One month, no problem; 2 months should be OK, 3 months starting to get iffy, and 4 months about a 50/50 shot it will start the car.
The unknown is how much current the car's electronics use while the car just sits? My T'bird ('04) will run down the battery in 2 months. My other cars last much longer.
If you don't have one, I'd recommend you get a "jump start" box. Sold by all auto parts stores, Sears, Walmart, Target, etc. Figure it will be $30 to 50. Then you have a quick fix if you go to start the car and the battery isn't able to do it without some help.
I use my jumper about 2-3 times a year either on the boat, or the T'bird, or if I leave the lights on by mistake. They come in handy. I think you'll be fine, but a jumper gives you a simple backup just in case.