What is the statute of limitations on Child Molestation in
Pennsylvania?  Does the clock start running at point of discovery or
point of offence?  Who do we start with, the Attorney General of
Pennsylvania, Police or whom?

This is just a free comment.
Talk to the police if you are sure you want to start a case. 
Attorneys will often give a brief free telephone advice.

The Pennsylvania statute of limitations for sexual offenses against
children does not start to run until the child reaches age 18 (on the
theory that, before then, he/she is not competent to decide whether or
not to file a complaint). Then, the statutes of limitation vary,
depending upon the severity of the underlying offense. For example,
the statute of lims for "sexual abuse of children" is 12 years. So,
charges could thoeretically be brought any time before the child turns
30. This appears at 42 Pa.C.S.A. 5552. ("Pennsylvania Consolidated
Statutes Annotated") However, police will be more interested in recent
crimes (or crimes recently discovered by the parents/guardians) so
don't put it off too long if you are going to go forward.

Start with a paid meeting/consultation with a CRIMINAL attorney, who
can advise you on what the process will entail, even though you will
not need a criminal attorney yourself (and may not need an attorney at
all for the defendant's criminal proceedings). In addition, some
places have victim advocacy groups who can also help guide you through
the process. Call your county district attorney's office or courthouse
for that information. Then, if you decide to pursue it, contact the
police having jurisdiction over wherever it happened. Suggest you
request a first appointment with the detective/officer who would be
assigned, without the child. (The child will have to be interviewed
soon thereafter, assuming he/she is old enough to remember and
communicate.)

There are also civil lawsuit possibilities. Most attorneys would
advise against that before all criminal remedies are complete. Also,
police/district attorneys may not like thinking that you are using
them to help pursue a claim for money....

Good luck, and God Bless!