For what it’s worth, I was the one who originally suggested the change in wording to “start with X safe days” and I meant how many days until derailing, just like @byorgey interpreted it.
I think it should work as I originally intended and @byorgey interpreted it.
Perhaps change the text from “X days of safety buffer” to “X safe days” or “X days until derailment” to emphasize that we’re talking about the critical edge vs. the centerline / flat spot problem. You can add an info tooltip that explains the details further. Something like “As soon as you create a goal, the clock starts ticking for you to make some progress. By default, we give you 2 days to make your first entry, but you can give yourself some more time here. Any additional days beyond 2 will give you a flat spot before the graph starts climbing and requiring progress.”
Alternatively, the text should be renamed to something like “Start with X flat days” or “Start with X extra safe days”, although I think this would be a little more confusing to newbees. I don’t think we should overload newbees with the idea of having flat spots on the graph, and IMHO, it never made much sense for most people to start a goal with a large safety buffer anyway; I usually only start a goal when I’m pretty sure I’ll be entering in a positive datapoint within 48 hours. I assume that’s one of the reasons why we’ve moved from the previous default of a full week of safety buffer in the first place.