Luggage Drop and Check In Time

This whole 'pre book your check in time' with Carnival is throwing my planning off!

We are staying in Condado the night before our cruise as our flight arrives in the evening. On cruise day I want to catch a cab to the pier, drop off my luggage, and do the part 1 and 2 walking tours listed here: puertoricodaytrips.com/old-san-juan-walking-tour-1/

How early can I drop off my luggage with this new system?

How long will the walking tour take so I know when my check in time should be? I will have a 7 and 10 yr old with me, who will want to rest and also play at the fort/in the fields, also work in time for lunch.

Thanks.

Hey Tinkerbell, I'll be on the Fascination too! Other posts have noted that you can drop your luggage with the porters anytime and then go explore. As for the check in time, when we used it in Galveston we couldn't check in prior to our time but could anytime after.