Performance wise I know we should avoid having scalar functions on the left side of the equal in the where clause. Anybody have an idea on how to avoid it in something like below?

Thanks

Select min(sdatetime) as FirstDate 
from dbo.Meetings (nolock) 
where iscancelled=0
and roomclosed=0
and isblock=0
and substring(scheduledBy,1,4)<>'TEST'
and substring(scheduledBy,1,3)<>'CQI'