Flutter - ListView.builder: Initial scroll position

I want to setup the initial scroll position of a ListView.builder, I want the list to start at the bottom 0.0

If I setup reverse on the listView of course I get the initial scroll position to be the desired one, but what I need is to have the last children on the bottom, is a chat app.

This is the list builder, MessageItem() is the chat message

ListView.builder(                    shrinkWrap: true,                    controller: _scrollController,                    itemCount: snapshot.data.documents.length,                    padding: EdgeInsets.all(10.0),                    itemBuilder: (BuildContext context, int index) =>                        MessageItem(                            index: index,                            document: snapshot.data.documents[index],                            myId: myId));

This is the animation I have when someone send the message

_scrollController.animateTo(                _scrollController.position.maxScrollExtent,                duration: const Duration(milliseconds: 500),                curve: Curves.easeOut);

the animation works okay.

What I want is the list scroll position to be already at the bottom when the user enters the chat room.