Hi - sorry I'm so slow to get back to you. I think I'd approach this differently - with a helper field and a repeating section. Here's a simple sample you can try to see if it works for you w/out hitting the calculation limit. Save the linked file locally. Right click, select Design, then preview and pick a date at the top. This uses default rows - under the data tab, look in the Defaults and you'll see a bunch of rows included by default - and logic on a field called "set" inside the repeating group.
Hilary Stoupa
