 The last novolog should be completely worn off in 0-0 hrs. The levemir will take a couple hours to start having effect. In the setting of an IV drip in the hospital, we give the levemir then wait 0 hours before stopping the drip. In this situation, I would do something similar. If you use a CGM, it will make it easier to minimize wide swings with the transition. When I go off pump, I use NPH, so slightly different onset and peak, but similar idea. As far as time of day, that would be up to you. I am unaware of any evidence of a clear benefit morning or night (as far as before knowing how an individual body reacts), but clearly it is easier to deal with swings with a morning timing while you are awake for the day rather than night and potentially having trouble while sleeping. 