aging formula with network days from start to today

=IF(AND(H753="",G753=""),"",IF(H753="",TODAY()-G753,H753-G753))
Trying to make the above formula return the networkdays from Start date to Today if there isn't a completion date.
In my data G is the start date and H is the complete date. If H is blank I need networkdays as of today.\

Thanks in advance