You'll be amazed at how naturally things just work out and how quickly you become adept at making these seemingly gargantuan decisions. :-)
Just pay attention to the important things like having enough food/water and carrying/protecting your shelter and you're good to go. You have a bit more challenge SOBO due to the more remote starting location and the first few miles, but you WILL survive and thoroughly enjoy yourself.
As one of the regulars on here like to say, "It's only walking". For the most part he's right. Sure there are a lot of things to consider, but none of them are all that important that you can't improvise your way around a bad or incorrect decision.
As the first respondent said, RELAX.
Good luck, and have a GREAT time.