When to carry?
Sub -Title: Can of Worms.
Carry as close to 24x7 as possible. Make it a habit 'cause when evil rears it's ugly head, it usually doesn't have an appointment. If I knew the date/time/place of when evil was going show, I would stay home...and if it was going to show up at my door and I knew this ahead of time, I'd call 911 and wait inside with an AK and a few extra mags.
Think about this - the last time you slipped and fell on your butt, did you know you were going to do just that when you woke up that morning?