Loop through sqlcmd command until condition is matched

SQL Server Administration
1

Am trying to loop through the below code until the count returns value greater than 0 (Each iteration should get paused for 5 minutes).
Once count returns value greater than 0 it has to exit the indefinite loop and fire insert query to specific table.
Am connecting to sql server DB

for /f %%a in ('sqlcmd -S -d -Q "SET NOCOUNT ON; select max(dt) as dt from prm"') do set var_dt=%%a

for /f %%a in ('sqlcmd -S -d -Q "SET NOCOUNT ON; select count(*) as cnt from Table2 where dt=cast('%var_dt%' as datetime)"') do pause 5 set var_cnt=%%a