I've been on this stuff once. (Hopefully never again.) The doc put me on 20 mg, but that wasn't enough, so upped to 30 mg after 5 days of no change in symptoms. Anyway, I always took it in the morning. This didn't help the insomnia.
There are other drugs that you can take if prednisone doesn't work, but I can't say that they're better in terms of side effects. I'm lucky that the prednisone worked for me, because I've had a positive ppd and can't take many meds due to the chance that I could get active tb. Talk about scary!
Good luck! I hope that you feel better soon.