Hi,
it's all good. You just need to be careful. Here's my thought, fly into Paris or Vienna. Bike into Italy. Since you have a whole month,
enjoy the city for a couple days, play the tourista while you recover from jet lag. If you start in Paris, you can enjoy Southern France, and then on into Italy. You could opt for a more diverse, and strenous, trip by going through Switzerland, Austria, and then Italy. That one would be nice. You could go to Salzburg (Augustinerkeller!) and then follow the Danube into Vienna. Set a day or two aside for Vienna. I loved Vienna. Then you would be well positioned to ride to Venice, and then across Italy. There are some tough choices as to which parts of Italy to visit, even with a month to play. There are many more possible itineraries, like flying into the BeneLux, or even Denmark. Might make more sense to reverse
the progression, and start in Italy, and ride north if you are starting in the middle of the summer.