Oh, poor Archer...
I have been where you are. My first cross country was one that caused me much anxiety and loss of sleep. And it didn't go well, either. I planned and planned, and re-planned. And I planned it right, too. When I called FSS I couldn't talk because I was so tongue-tied. The briefer was amused and helped me as much as she could, which was a good thing!
Then we took off, and I started looking for a checkpoint, which I found, but I couldn't do my calculations. And by the time I had some numbers written down, we had passed the next checkpoint. I couldn't fly or think by about 20 miles into the trip. My instructor refused to help me at all, and I was furious.
When we got to the destination airport, he wanted to eat lunch, but I was in the bathroom throwing up. Sounds fun, huh?
Don't be like me. I worried myself sick, literally. And it was unnecessary. Even after all those screw-ups, I made it there. I found the airport and we landed safely.
Now, fast forward 5 years and I'm an instructor. I can honestly say that the experience was good for me, because it has made me a better instructor. I have been there. I have felt what you're feeling. And I can surely relate.
When I have a student who is overwhelmed with the planning process, then we do ground and plan and plan and plan. I try to get them to use an old sectional at home and plan hypothetical trips just for practice. Then they bring in the planning to me and we go over it. I try to give them sectionals that are out of their area so it's unfamiliar. We plan the real proposed trip once without actually flying. Then we plan the trip a second time and go. If they are still feeling overwhelmed, then we plan a "short cross country." That's where we plan a trip to an airport that's only about 30 miles away and just practice finding checkpoints and doing the calculations and using the E6B. There's no pressure and we can take as long as we want.
One suggestion for you (if your instructor hasn't already offered it), make your checkpoints no less than 15 nm apart and no more than 20. If they are too close together, then you'll pass over the next one before you get your calculations done and logged. If they are too far apart you have time to wander off course (if, say, your compass hasn't been reset or the winds are different from the forcast). But inbetween those, find ones that are marked on your chart that are just to make sure you are still on course. Highways are good ones, and so are railroads. You don't have to do your calculations at those, just make a note on the chart that you've passed them.
All of this really is supposed to be fun. I make every effort to have a good time with my students, no matter what we are doing. Cross countries are serious stuff, but also probably the funnest part of your private training, because it's a culmination of everything you have learned so far.
There was an earlier post from a guy who said that after he got his private he never did planning anymore. That was inappropriate, in my opinion, for this thread. Unfortunately, in a public forun he has just as much right to post that as I do to post thig. He may not do planning anymore and that's ok for him, but it's a dangerous attitude for someone like you to develop this early in your flight training. The FAR's require that you have all available information before you go, and that means doing your planning and calculations to know if you'll have enough fuel and how long it will take, etc. Your method of planning may change, but you should still do it. When I fly for pleasure, I plan the trip and do the times. When I flew charter, we were required to completely plan the trip and note times and fuel consumption. When I flew freight it was easier because it was the same route every day, but I still figured winds aloft, because I needed to know how much fuel I would need for the trip. And, of course, W&B is a must for all of those things. As an instructor, I am an example to students, so it is doubly important that I do things the right way. The GPS is a great tool, and if you have one, you should use it. But at this point in your flight training, the goal is to learn pilotage and ded. reckoning. So don't turn on the GPS until you've got the fundamentals learned. It will only hurt you in the long run.
I can't wait to hear how the first trip goes. Don't feel pressured to make the trip just because it seems like times a'tickin'. Wait until the weather is right and you are ready and you'll be just fine. I have seen at least one offer for a flight planning checklist. I have one, too, if you woud like it. Just let me know. Good luck! And have fun!!
Rachel