Guess I better get running

Signed up for the Across the Bay 12k. This is about the furthest distance I've run, but I've run 5mi to 10k distances many times. Biggest difference is that this is the first time I'm doing it willingly, and I won't have sing cadence the whole way. I ran 45 minutes today, would guess about 5 miles, but don't know. But the main thing I need to do to get ready for this (it's only two weeks off) is to start getting to bed earlier.