If you're running only on Mondays, these formulas might help you. If the day can vary, you might need an additional operation.
select DATEADD( hh, 7, DATEADD( dd, DATEDIFF( dd, 0, DATEADD(dd, -7, getdate())), 0)),
DATEADD( hh, 7, DATEADD( dd, DATEDIFF( dd, 0, getdate()), 0))