According to most the theories I've heard, you should take both in the morning to limit HPTA suppression.
As to how much it shuts you down, I haven't seen any studies, but I do know one local doctor that says the three times he's had patients that did 10mg every morning and had blood tests, it reduced their natural production by a minimum of 40%. If I remember correctly, he said one guy's test production dropped by just over 60%.
Unless someone convinces me otherwise with a study, I'm not going to do a dbol bridge. It sounds nice in theory.