How early in the morning should i depart Sorrento to catch a 6.30 am flight from Naples?

I believe you’ll need to book a private driver

Or better yet-spend that last nite in Naples

You need to spend your final night in Naples. It's too risky and way too early.

Agree, that last (v-e-r-y short) night should be spent in Naples. You'll have to get up at oh-dark-thrity anyway, even from there for a 6:30 am flight. Starting in Sorrento...you would need to cut short your last dinner!

Based on these responses we are changing our travel plans and depart instead from Rome which has departing flights at more reasonable time. thanks.

Is it even possible to leave early that same morning from Sorrento?

Theoretically, yes.

As a practical matter you would have to get up, assuming you could go to sleep, around 230AM to take a cab around 330 to get to the airport between 90-120 minutes prior to flight time.

I know you wanted Sorrento at the end to finish on a relaxed note, but given the what to me is the grim choices of an early flight would have made me end in Rome for a departure at a more civilized time.

edit-- I type slow, so did not see OP had posted he has decided to change

I hope you are planning to be IN Rome the night before your departure flight.
Even it’s a later flight trying to get from Sorrento to Rome ON departure days is too risky

yes we now plan to spend the last several days of our trip in Rome (instead of Sorrento)...thanks all for the advise.

Shekar, you didn't say whether the departing flight is to the US or within Shengen zone. The three hour requirement for US flights is partly for Homeland Security demands for passenger list submission a certain number of hours before the US arrival. It's not just a caprice of the airline.

You don't say if you will be spending the last night in Rome. It takes at least THREE trains to get to the Rome airport from Sorrento. So unless the plane is after 3PM, it's pretty risky to do that from Sorrento. And if you are using the (fast) Frecciarossa service, your discount tickets will be for only a single specific departure time from Naples.

Month of the year makes a difference, because of crowding. Especially for Economy class check-in.

The OP said:

"...we are changing our travel plans and depart instead from Rome which has departing flights at more reasonable time."

"....we now plan to spend the last several days of our trip in Rome."

So they'll be fine. :O)