Recreation.gov ?

I recommend calling the contact number for the campground you want and asking them. I think the 10 a.m. EST is a default setting that recreation.gov uses, but that any "owner" or campground entity could change that to their own particular preference (e.g., 7 a.m. local time; 12:01 a.m. EST; etc.).

Ok thanks! I just talked to a customer service from recreation.gov and they said 10:00 am EST. But that doesn't seem right because this morning I was in Recreation.gov and they were taking reservations this morn at 5:10am EST for RMNP for July 23,2017, so really don't understand it at all. Too confusing. LOL

I imagine it varies, Yosemite if I recall right, sites go onsale at either 7 or 8 AM PST. You have to check to see which it is. I have no idea when Bahia Honda sites hit the market but those are on ReserveAmerica. I looked at the website but got no clue other than 11 months in advance. Call them on the phone and you may get an answer. They do mention that the phone is manned from 8 AM to 8 PM so that might be a clue.