There is no such thing as being too young to apply for life insurance. In fact, the younger you are, the lower your premium is likely to be. This is because the possibility of a 30-year-old outliving a 20-year term policy is very high compared to a 60-year-old.
Waiting till you get married or have children may not be wise, as there's no way to ascertain the future. Also, health problems can arise unexpectedly, so it is best to be prepared for such emergencies.