Thank you for the clarifications.
We are loading jQuery from Telerik.Web.UI which is used by our ASP.NET AJAX controls, an in addition to that the jQuery core is loaded you can make the reference $telerik.
Out of the box $(document).ready() is available but since you are making controls you have to make sure that jQuery is used
<%@ Register Assembly="Telerik.Sitefinity" Namespace="Telerik.Sitefinity.Web.UI" TagPrefix="sf" %>
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