SaveChanges of datetimepicker on ValueChanged

I use the following code to save the selection of a combobox to the SQL server and then filling a datetimepicker with the according value:

var comboboxSelection = Context.SomeEntityA.First();
Context.SomeEntityA.Update(comboboxSelection);
comboboxSelection.SomeMember = projectIdentifier;
Context.SaveChanges();

var someList = new List<SomeEntityB>();
someList = Context.SomeEntityB.ToListAsync();
private BindingSource _someBindingSource = new BindingSource();        
_someBindingSource.DataSource = someList;
datetimepicker1.DataBindings.Clear();

datetimepicker1.DataBindings.Add("Value", _someBindingSource, "StartMonth");

What do I have to do to save the selected date of the datetimepicker to the server on ValueChanged event? The following code won't work:

private void datetimepicker1_ValueChanged(object sender, EventArgs e)
{
Context.SaveChanges();
}