i just had this done to my house in greece....having watched the men do it, i realised how easy it was, i could actually have done it myself. it is very simple to do. first you make sure the floor is level and clean, no gobs of cement if it's a cement floor. then you place down a piece of plastic, you can get them in huge sizes, then you place down a special sheet foam stuff on a roll that you buy with the wood, then you just start laying the planks next to each other, they all fit tongue-in-groove and pop together. some you will have to cut obviously, but this can be done with a laminate tooth saw, and a sharp blade knife.....there are how-to books that show you this step by step....
i dont think the time of year has anythign to do with it. ask the store where you bought it if they have any contacts for laying the floor you just bought! good luck.