This is one of those funny things that's a carryover from when almost all schools had in-house driver's Ed.

You can enroll in a student driver course with a PA licenced instructor at 15 years of age. With your enrollment you will be eligible to obtain your permit and begin building your required supervised driving hours, but you must pass the written permit test as part of your enrollment, if you don't pass the knowledge test, no early permit/driving school.

If you do pass and get a permit you will have to complete the student driver school and have a certificate of completion to present at the DMV to schedule your road test. The road test cannot be taken until you are 15.5, so around July 22.

If you pass your road test you can indeed be a licensed driver before 16.

If you cannot enroll in a driving school you're basically SOL until your 16th birthday.