@gravity3 (and also @newenglandtransplant, @windyshores, and @normahorn) As you mention the Amgen - Prolia website does clearly state that a wait of 30 days plus or minus 7 days was used for the Frame study. "*In the FRAME study, Prolia® was initiated 1 month +/- 7 days from the last monthly dose of EVENITY®." So a period of 23-37 days was used.
From: https://www.evenityproliasa.com/evenity-to-prolia-transition

I tried yet again to find more info on how long after stopping Evenity before you go to the next med. I found no clear discussion of this. I looked at one or two studies that went beyond 1 year and had a follow up med after Evenity. Maybe I was just looking at the Frame study or the extension to it. Anyway I could not find a statement specifying a time period. What I did see is that there is an implication that a 1 month period after Evenity was used. The studies would specify months 1-12 and then 13-24 or endpoint 24 etc. If patients were taking the next med starting at any date other than the next month I believe it would have been specified because when you state months 1-24 it does imply that months 13-24 were on the follow up med. My unverified conclusion is that those studies were doing the next med at 1 month after the last Evenity shot.

That does not prove 1 month is ideal but it does show what we have data for. There may be no study data available for any other length of wait time?

And here's Amgen saying start follow up at 1 month.