Just as we were taught in grade school, it is important to be on time. Nothing says rude in business as loudly as not being on time for your appointments. It is plain disrespectful because it indicates that you are not appreciative of someone else's time. If someone has committed to spend time with you, you need to be respectful and make an effort to show up on time. Recently I was at a networking event where someone was late. I could tell from the conversation of the group that this is very typical for this individual to the point that the group was kind of poking fun at him and when he finally walked in someone made a comment about his tardiness. I ask you, do you want to be this guy? His reputation (and not a good one) preceded him. If tardiness is something that you struggle with you should make every effort to improve in this area... for the sake of your business.