Need advice as to when I should start contacting hotels/B&Bs. I'm most concerned about Venice, Florence and CT. I also don't want to have our reservations lost.
Contact them as soon as you know your itinerary. We visited Florence last October, after booking our room the previous March. As for losing your reservations, just follow up with your hotel/B&B once or twice to confirm as the big day approaches.
We went to Italy last September & I booked all reservations anywhere from 9-11 months in advance. Might sound premature but the places I wanted to stay in were highly rated on Trip Advisor and I knew they would book up fast. I had no issues in terms of lost reservations and I did what the other posters are suggesting...I followed up 1-2 months before our trip to re-confirm. Had no issues. Have a wonderful trip.
Be certain to submit your dates in the correct format. Europeans use the DD/MM/YYYY format whereas we use MM/DD/YYYY. I think that this is why reservations are sometimes lost. Better yet, spell the month instead if possible. Also, double check your reservations for the correct dates. I have had numerous reservations nearly bungled because they entered the wrong dates.
Scott's point is important. Also, September is still busy, but not overwhelming, so there is no huge hurry, but go with what makes you comfortable. Another factor to consider, is the deal you present to a hotel. If you are booking long in advance, for a very short stay, and maybe even a single, don't be surprised if you get no reply, or a negative reply as to availability. Many hotels, like some in the CT, may hold out for doubles staying 3 or 4 nights, or booking a whole weekend as opposed to just one night. In these cases, it never hurts to contact a hotel closer to your trip to re-check on availability. It is amazing how often an opening may "come up"
Thanks to everyone for the great advice!