Getting professional business cards made can get to be pretty expensive so a lot of people try to put off ordering them. There are people who really don't need them and there are people who absolutely have to have them. The question then becomes when is the right time to get professional business cards made? Unfortunately there are no easy answers to that question since it will largely depend on your individual situation.
The best time to get professional business cards made is as soon as you go into business. You are going to need them so the sooner the better. You actually find the cards to be useful in the early days of starting a business since you will be meeting lots of people and trying to establish contacts at this stage so you will find the cards convenient to have. Most people in the early days are trying to save money so they will often avoid expenses like business cards. However this is not really a good way to save, you really need the cards.
The other people who really need to get business cards are the ones who are out looking for a job. Again this is a group that really needs a business card but often avoid getting them to avoid spending the money. One of the keys to finding a job is networking; you are going to want to give your card to everybody that you meet since they might be able to help you find a job. This is especially important for new graduates out looking for their first job. Often they won't have a professional business card but they are the ones who need it most.
If money is really tight you might want to avoid getting professional business cards and go with something cheaper like premade cards through 123 print. Although this is far from the ideal situation it may be necessary until you get your business up and running or you find a job. In this case you are going to want to use a more basic business card that is based on a pre-made template. You will of course still want to make sure that you get a card that looks good.
The one group of people who absolutely need to have professional business cards is anybody who is involved in sales. A sales person will give out lots of cards and the people they are giving them to will likely receive lots of cards, especially if you are in business to business sales. In any case you are going to have to have a card that looks professional at a minimum. Ideally would like to get a card that is unique and really stands out. This will help to increase your sales since the person you gave your card to will be far more likely to remember it.