Out put for the report should be after completing the data loaded

Hi Every One,

I have issue like when the data is loading, report should not be executed till the data loaded completely. After finishing the data load, report should executed if not msg should display like"'DATA NOT AVAILABLE, PLEASE WAIT" for the user. because if some one using this reports in between the data loading they get missing data so instead of that they should not get executed till data load finishes completely.

This procedure should apply for many reports like this so i need a solution to automatically do this step.....

So can any one please help me in this issue....thank you very much for spending your valuable time.