If you tried something like:

with cds1.Params do
begin
  ParamByName('finish').AsDateTime := now;    
  ParamByName('start').AsDateTime := Now-1;  
end;
cds1.Open

And you received error like: DBX Error - ParameterNotSet then don't use AsDateTime, use AsSQLTimeStamp := DateTimeToSQLTimeStamp(Now-1);, so your code should look like:

with cds1.Params do
begin
  ParamByName('finish').AsSQLTimeStamp := DateTimeToSQLTimeStamp(now);    
  ParamByName('start').AsDateTime := DateTimeToSQLTimeStamp(Now-1);  
end;
cds1.Open