Hi,
there are a few solution to this.
1. If you're a firm believer to feng shui, you should choose a good date to start reno works, consult a master (i can recommend if you want)
2. Get Joey yup 2010 calendar (popular book shop got sell) and select the date from the calendar. It's simple and I am doing it this way.
Actually, knowing the time to start reno works is also very important unless u want to be that detail.