If you realize midway through the application process (when you get the appraisal)that the collaterl will be under 25 acres, do you have three days from the realization to mail the early disclosures or must it go out the day you get the new information?

That situation is not specifically addressed in RESPA. However, you would need to provide the disclosures as soon as reasonably possible after obtaining the information. I would consider within 3 business days to be reasonable.

Thanks. As usual I now have a few more facts. We had the appraisal fairly soon but missed the fact that the property was under 25 acres until a few days before closing.
So, the date when we should have discovered the acerage would start the 3 days, not the date we actually discovered it, right?