You need to make an edit to PageConfig.xml. The file is in your \Web ASPx\WEB-INF\xml directory. You want the Report Execution node, so search for:
<page desc="Report Execution" desc-id="" feature-id="" login-required="true" name="report" persist-mode="8" track="true">
Once you're inside that node, you need to fidn the Report Web Bean.
<web-bean bean-type="md" name="rb" persist-mode="2" sys-bean="ReportBean">
Within that bean will be two initialization properties, the first which is:
<property name="maxWait" source="const" type="int" value="2000" />
Change the value of this node to -1 (see below.)
<property name="maxWait" source="const" type="int" value="-1" />
Restart IIS. This will remove the intermediate Wait page. (You can also find rough instructions for this in the Web SDK documentation.)
Ming