Upvote:3
I have almost the same issue for a planned trip to South Tyrol next week (I might stay at multiple places and perhaps not sure when entering Italy exactly where I will be staying) and I just called the information hotline mentioned at the beginning of the form.
If you know the first location you are planning to stay, you should enter that location, or at least an approximate. The address of stay is just a text field and you can also mention or explain there what you know when entering and that staying at further locations is planned, but you don't know exactly where.
Quite honestly, I doubt that this information will be used for anything particular at all.