Hi,
There's nothing much to know here. Just get to Nanavati on time they want you to report. Maybe get there a bit early(it will be easier to pay the fees for you). Everything is included included in the fees(unless the report shows some problem and you have to consult other doctor). They give you breakfast and lunch on the first day. You will have to visit Nanavati twice. Once for the tests and the second time to meet the president who will give you the certificate(he comes only on Wednesdays and Saturdays). If there are any problems in your report they will tell you to take medication or necessary counter measure and return. They are quite systematic (at least when I visited them).
On the day you have to meet the president, come on time. If you're late and if he has left you will have to come again.
Just be calm and come with a mindset that you might have to wait till 6 and visit the hospital again.
All the best.