I reckon that people spend to much time worrying about things that are beyond their control, worrying over things that they can't possibly do anything to change or improve.
* What if the sky falls on my head tomorrow?
* What if something bad happens while i'm away on holiday?
* What if this happens when that happens due to this other thing happening?
The solution is to make plans, and to trust that things won't go wrong when there is no reason for them to go wrong. You've taken all the necessary precautions. You chosen the best circumstances available to you to get the job done; there really isn't a single thing you could have done differently up to this point. You've got a back-up plan in store, just in case. What more can you do? By worrying what could happen despite all your precautions, you just make yourself feel miserable.
There really is no point worrying about things you can't control. Worry about things you can.