I rarely reserve anything in Italy that far ahead. I just wing it and book online a day before. Two years ago I decided to take my wife and sister in law to Val Gardena at the last minute and made reservations on hotels.com from my italian Iphone while driving there (ok I pulled over at the Autogrill to do it). It was July, so even high season. Few years ago I did the same thing in Rome, and Verona, and you name it. You may not get the exact hotel you want, but there are accommodations available anywhere at any time. The only time it's really tough is the last week of April in Rome or Florence (two national holidays April 25 and May 1). Venice is tough year around, so reserve ahead for Venice. Anyplace else you can wing it, but you need electronic devices (tablets, phones) with wifi capabilities to search and book on the go. Lake Garda will be full in July and Auugust but not May (but there will be people on weekends for sure).