Deeper if then logic for existing fomula?

I have the below formula to see how many days between dates for projects:

=IF(I19="",NETWORKDAYS(H19,TODAY())-1,"")

So kind of works, but doesn't work if the H column is blank as well. How would I get this logic.

The "H" column is the start date
The "I" column is the End date.
Start date is blank if not started
End date is blank if not completed.
Start date is assumed to be today to show total duration of the project

Looking to have a single formula for column "J" of duration that says:

If Start Date is populated and Completion Date isn't, use like I have above.
If Start Date is populated an Completion Date is populated diff them.
If start date is blank and completion date is blank return blank or 0

Right now the above formula if start and end are blank will return 30665.

Thoughts?

Thanks.

JR

Been playing with it, below gets everything unless both start and completed exist.

=IF(AND(I19="",H19=""),"",IF(I19="",NETWORKDAYS(H19,TODAY())-1,"")))

Maybe this?

=IF(AND(I19="",H19=""),"",IF(I19="",NETWORKDAYS(H19,TODAY())-1,NETWORKDAYS(H19,I19)))

Thanks Aardigspook, just saw your response.