Plotly: How to display graph after clicking a button?

I want to use plotly to display a graph only after a button is clicked but am not sure how to make this work. My figure is stored in the following code bit

    fig1 = go.Figure(data=plot_data, layout=plot_layout)

I then define my app layout with the following code bit:

app.layout = html.Div([
                #button
                html.Div(className='submit', children=[

                html.Button('Forecast', id='submit', n_clicks=0)
                ]),
                #loading 
                dcc.Loading(
                id="loading-1",
                type="default",
                children=html.Div(id="loading-output-1")
                ),
                #graph
                dcc.Graph(id= 'mpg-scatter',figure=fig),
    
                #hoverdata
                html.Div([
                    dcc.Markdown(id='hoverdata-text')
                ],style={'width':'50%','display':'inline-block'})
])

@app.callback(Output('hoverdata-text','children'),
             [Input('mpg-scatter','hoverData')])

def callback_stats(hoverData):
    return str(hoverData)


if __name__ == '__main__':
    app.run_server()

But the problem is i only want the button displayed at first. Then when someone clicks on the forecast button the loading feature appears and a second later the graph displays. I defined a dcc.loading component but am not sure how to define the callback for this feature.

from Plotly: How to display graph after clicking a button?