Buy the computer ASAP and use it as much as possible before coming. Do not wait until the last minute to buy your computer! There was a post a month or two ago from someone who had a friend bring a computer to him from the States. The OS had been activated the night before and ADUANA (customs) charged a 50% tax on the computer.
For my next computer I will have my brother buy it, and use it for a month or two before I even see it. It will have crap all over the desktop and will obviously not be brand new.
BA isn't the 1st World. Don't treat it like it is. You will feel all sorts of pain if you do.