Getting intraday volumes

I am using below code to get volume. However I am getting empty bars until 9 AM EST or bit later. Can you please guide

session_start = now.replace(hour=4, minute=0, second=0, microsecond=0)

today_request = StockBarsRequest(
symbol_or_symbols=symbol,
timeframe=TimeFrame.Minute,
start=session_start
)
today_bars = client.get_stock_bars(today_request).df

Can someone please help how to get current day bars