After a hard workout, most people begin to experience soreness within 24-48 hours in the body parts that were trained. This aching is known as delayed-onset muscle soreness (DOMS) and can last for up to a week after first setting in.
Working out should be challenging, and some soreness is normal - especially when first getting started with a new fitness program. The more your body adapts to the workload you impose on it, the less soreness you'll feel. In fact, if you continue to repeat the same workout over and over again, it will eventually cease to make you sore. However, at that point you will also cease to make any progress because progressive overload is the key to getting stronger and toned.