>>You can use some arbitrary number, say, where RowNumber between 2 and 1000 and otherwise the condition will remain exactly the same as my original select statement.
>
>Yes, but you need to know the limit. That is why I opted for COUNT.

Try (from the top of my head - play with the idea):

;with cteRanges as (select *, row_number() over (partition by ClientID order by DateCol desc) as RowNumber,

 row_number() over (partition by ClientID order by DateCol desc)  - row_number() over(partition by ClientID order by DateCol desc,
case when status = 7 then 1 else 2 end) as Grp from Invoices)

select * from cteRanges where Grp = 0 and RowNumber >=2