Urgency can be a great tactic, but it has to be used properly. Urgency tactic should actually be helpful to the user. You are trying for the customer to come to a decision on whether or not to make a purchase, at least faster than they would have done. If you overuse it, the costumer will ignore you.
Urgency messages are usually use for:
A message advising that they only have a day or two to take advantage of sales offers, tells the customer that they need to decide quickly before there are none left.
An alert indicating how many people have already bought the product or how many items are left, make the urgency signals more credible. Also, people are much more inclined to buy something when other people desire them too.
Even a message of how many people are looking at the page could push some users to make a decision faster.
Use a different color to set it apart from the rest of the text. Red usually makes it more visible.
Promotions with a limited time
A message about a limited time sale plus a trend of rising prices tell the customer that they need to act fast.The desire to avail free delivery, for example, could possibly offset the visitors’ tendency to procrastinate the purchase
A countdown timer for next day delivery on your shopping cart pages provides an extra push for customers who want to avoid problems with goods arriving too late for birthdays, Christmas etc.
Urgency is a powerful tool. It gets prospects and clients taking action. However, do not over use it. Too much urgency on a limited-time offer or a stock shortage and your customers will let it pass. Moderation is the key, though testing will give you better insights as to what will work for you.