It depends what weight you were to start with really. If you have a lot to lose then just the first 5lbs won't be all that noticeable, as it's just a small percentage of your overall weight. If someone was already average or under weight and lost 5lbs it would be more noticeable as the 5 is then a bigger percentage of her body. Bear in mind that the first few lbs lost on a diet is usually water weight, so although you will weigh less on a scale your measurements will be the same as you haven't burned off any significant amount of fat yet to affect your size/shape.
5lbs is still a decent start on your journey though, and most people notice a real difference at the 10lb mark, so keep it up! :)
I agree with everything CuteNsweeT said, plus I'd like to add that it would depend on where you lost the weight from. When I lose weight, it's usually my face that shows it first, so of course, my clothes don't fit any differently. I also tend to lose it more quickly from my upper arms, which also doesn't show much.
As CuteNsweeT said - the more you have to lose, the less likely the first few pounds will show much. I had a friend who was obese, began exercising and lost 10 pounds right off the bat, but it really didn't show. It wasn't until she'd lost about 30 lbs that you could actually see it. Unfortunately, she didn't stick with the exercise and gained it all back!!
A good thing to do is to measure yourself, in addition to weighing. By taking your measurements you can keep track of inches lost, as well as pounds.
I agree that losing 5 pounds is a good start on your journey, so don't get discouraged and give up. Congratulations.