Early AM Venice Flight

Is it directly back to the US, or are you changing planes somewhere before the transatlantic flight? Flights directly to the US usually don't leave that early.

Change in Belgium...

Then it is a "domestic" flight, so checking in by 6 am should be sufficient. You'll go through Schengen exit passport control in Belgium.

Ah gotcha thank you-what do you recommend for getting to airport?

Book a private water taxi
Probably about 120 euros but worth it given your group and time of departure
https://www.motoscafivenezia.it/en/

If you Airbnb is not on a canal that taxi can access then you will have to walk to whatever dock or vaporetto stop is closest

Venice to Belgium ( BRU?) is a 'domestic' flight within the Schengen zone ( https://www.schengenvisainfo.com/schengen-visa-countries-list/)

It is in BRU that you will have the time consuming exit formalities

So getting to VCE by 6AM should be adequate.

Ask you landlord for the options of getting to airport from the location

VCE-BRU-USA is all one ticket?

Thanks the private water taxi sounds good. Our tickets are Brussels Airlines from VCE to JFK via BRU (yes one ticket)

Then No it’s not a domestic flight...it’s international. You need to arrive by 5:30 at the latest. It’s a bit of a joke from the water taxis to the checkin gates at the airport.

Thanks, what do you mean joke from water taxi to gate? Meaning a walk?

From the water taxi dock to the check in area is about five or ten minutes. There is a moving footpath, so not all that much walking.

Gotcha, thanks. So best bet would be arrange private water taxi maybe 5 am, should be easy to make flight on time?

If you can get over to the train station easily, I'd take a regular taxi to the airport. It's much cheaper. You could make a reservation with a cab company to meet you on the Plaza.
Sometimes it's easy to get there, and sometimes the hotels are a little harder to get off The Island from.

Question for the OP.
Where is your hotel/Airbnb/whatever located?

Sestiere Cannaregio
Worry about trying to get two kids and bags to train station at 5 am...while I love saving $, this may be worth a little extra to make beginning a long day a bit easier. But open to advice-

And it is not "to the train station". From the train station it is then a walk over the long bridge across the Grand Canal to Piazzale Roma where you get a land taxi, about 600 to 800 feet.

If u prefer to stay nr airport Ck out Hotel Titian they have a shuttle and get passengers 59 terminal quickly. I have done 5his for an early am flight also. It is a best western hotel.

Already have lodging set, sounds like the private water taxi will be worth it for sanity at 5 am. Appreciate the help everyone!