I agree with Waz that you can use -DEFAULTH &var = value; if you haven't already done so to "disable" the autoprompt from popping up by giving everything default values.
In regards to setting up a simple message in place of the autoprompt facility popping up, you can supply a default value in a check at the top of your procedure/content to see if the form with the filters has passed its default values to the procedure yet or not by adding a hidden control (like a dropdown - calling it HIDDEN or something) to your form, and setting it to a static default value of like Y. The check at the top of your content would then be something like:
-IF &HIDDEN EQ 'N' THEN GOTO Wait;
Then at the bottom of your code, have something like:
-IF &HIDDEN EQ 'Y' THEN GOTO TheEnd;
-Wait
-HTMLFORM IBFS:/WFC/Repository/appFolder/subFolder/PlzWaitForFilters.htm
-TheEnd
This setup can be used for checking the hidden value, or even a value for a non-hidden filter like your wanting. If the user hasn't selected a certain filter value, you can check for that and then display a simple html message in place of running the report or graph until the user does select something for that filter.
Hope this helps!
8.2.02M (production), 8.2.02M (test), Windows 10, all outputs.