It would be nice to have 4 nights in Venice instead of three. If the AirBnB you booked can be canceled, I suggest you look instead at one of the reliable apartment rental agencies that we ourselves have used for Venice. I recommend this over AirBnB rentals for several reasons. For first-time visitors to Venice, it is nice to have the back-up and support of the management team if you need it. And the company will provide a representative to meet you at the nearest vaporetto dock and show you the way to the apartment and give you a little orientation before handing you the keys. They will also explain things about recycling and garbage collection, which can be confusing.
With AirBnB you are at the mercy of individual owners who may or may not be helpful, and the directions they provide to the apartment may or may not be sufficient. On our recent multi-day (5 nights) stay in Venice, in March 2023, there were 3 separate occasions where we saw visitors arriving with luggage struggling with the directions on their phone as they lugged their roller bags up and over bridges.
One time it was a group of 4 young women (Americans) and they could not agree on what the map directions on their phone were saying. I looked at the location, then showed them a paper map, and walked them to the top of the street they needed to take (it was nearby but they were heading the wrong way). The second time was a British couple who were very grateful for some help. The third time it was a German couple, in a confusing maze of dark streets in the area north of San Marco. The wife was in tears and the husband was angry, and I felt it best to not intervene. I hope they worked it out.
The two agencies I recommend are Venice Red House, owned and managed by Venetians, and Views on Venice, which I believe is a British company, but the on-site management is Venetian (the apartment we rented from them was right near their office, and when we had trouble with one of the keys they sent someone over in 5 minutes to help).
These are examples of their rentals on offer, available for 4 nights on your dates, both in a location in Dorsoduro we really like. But they have many other apartments all over the island. You can use the links to check out the two apartments and then move to the main page to look at others.
https://veniceredhouse.com/apartments-in-venice/venier-apartment/
https://www.viewsonvenice.com/rentals/apartment-venice-lo-squero-1-the-secret-courtyard-in-dorsoduro-324091.html?FRMEntrada=31/03/2025&FRMSalida=04/04/2025&FRMAdultos=2