Hi Jignesh you can better change your code like explained in the article of Jaroslav Kordula : http://devnet.kentico.com/articles/kentico-8-technology-documentquery-api
This worked for me where DOcumentCreatedWhen is your custom DateTime field :
var doc = DocumentHelper.GetDocuments()
.TopN(1)
.Path(CurrentDocument.NodeAliasPath, PathTypeEnum.Children)
.OnSite(CurrentSiteName)
.Where("DocumentCreatedWhen", QueryOperator.GreaterOrEquals, DateTime.Now);
// Go through the documents
foreach (var document in doc)
{
URLHelper.Redirect(document.RelativeURL);
}
Good luck!!!