The general rule of thumb is you should provide at least 6-10 times your income with a life insurance policy. However, you may wish to have more than that if you have a large number of dependents, an expensive mortgage, or other expenses that would be hard for your family to meet after your passing.
A substantial life insurance policy can be very difficult and costly to obtain the older you get because the risk of you needing the policy increases with age. Therefore, starting your policy while you’re still young and healthy is best, giving you time to let it grow without it being a financial burden and to minimize the chance that you’ll be turned down for coverage due to poor health or advanced age.