Cash value life insurance policies typically have a level premium, meaning that a higher percentage of your premium payments goes toward the cash value. Over time, the cash accumulation slows down and more of your payment goes toward the cost of your insurance, since it is generally more expensive to insure an older person.
The amount of time it takes to build up a cash value depends on the exact policy. Generally, there's no value within the first year. With a traditional whole life insurance policy, you can expect it to take at least 10 years to build up enough cash value to start taking advantage of it.