In instantiating the ImmutableString, the function pointers to the get and length methods actually refer to the String.get and String.length method, by going through the base variable which is an internally stored String object. The use of a function pointer can achieve inheritance of a method from a superclass.
Most women will start to show at some point between weeks 12 and 24 of pregnancy, with most reporting that they began to show during the first half of their second trimester, between 12 and 18 weeks.
Every woman is different. Usually it takes a little longer to show in your first pregnancy and most women show sooner in following pregnancies. I'm a larger lady and this is my first. For me, I didn't start showing until after 20 weeks and didn't start wearing maternity clothes until around 22-23 weeks. No real way to know until it happens:-)