Hello There,
I did this this exact tour in May of last year. Most start times were between 8-9 (every day is the same). You get your free Breakfast and meet the guide in the lobby between 8-9. Here what i remember each day of the free time.
Venice- I arrived a day early. Got to the hotel around 12 and after checking in and lunch i went to St. Mark's Basilica. I walked around inside and went to the second level to see the view of the square. So that is defiantly something you want to check out yourself. I would recommend pre purchasing the Basilica tickets. If you wait to in person the lines can be over an hour wait. (though they might be shorter for you in April then me end of may.
On the official Day 1 you don't meet till around 4pm with the group. So unless you are arriving you have most the day to yourself. I did this tour through Viator that was excellent. It went to places on the tour that Rick Steve's did not go to.
On Day 2 after the tour through Venice you get done around 11-12 and have the rest of the day to yourself. I went into the Doge Palace witch i bought tickets at the gate with minimal wait. Then i had pre-purchased tickets to the clock tower in St. Mark Square. I would recommend doing both. I then just wondered around Venice rest of the day.
Day 3 is when you go to the art gallery and the islands. You do have some free time on the islands, but its fun to just get a bite to eat and wonder around. You dont get back to the mainland till around 3pm. I then just wondered around.
Florence
Day 4 you drive to Florence have a tour of Florence and a tour dinner. No free time that day.
Day 5 you have another tour through the backstreets of Florence and the cooking class/lunch. After the cooking class/lunch ends around 1-2 you get free time. I Climbed the Dumo. I would highly recommend buying tickets for that ahead of time. They sell out weeks in advance. (not its a tough climb. you need to be in shape). Same with the bell tower. That night i went to sunset at the Piazzale Michelangelo. Something you need to do. Though note there a lot of people.
Day 6- After a guided tour through the Uffizi you have free time 11am to around 5pm. I went to the Medici Palace and House. Both you can buy tickets at the game with minimal wait or online to be extra safe. At 5pm you meet back up to go see the David.
Rome
Day 7- Drive to Rome and stop at the winery. Dinner in Rome with the group walking tour after dinner. No free time.
Day8- After tour of the Vatican Museums nd Sistine chapel your on your own at 11-12. You can walk around St Patrick's Basicala since it ends there. I ended up going to the top. but had to wait in line for about an hour. After that i went to buy tickets to castel sant angelo witch was worth it. Bought tickets at entrance and was fine.
Day 9- last full day. Tour the Colosseum and Ancient Rome- Afterwards you have free time. I walked around the palatine hill (witch i bought tickets at the gate) and some the other antient ruins that we did not go to. You then have to be back around 5pm for finale dinner.
I unfortunately had to fly back after the tour and had no extra time in Rome.
Hope this helps.