Howdy Mike - Texas Aggies? Texas A&M university?
So - at your age (similar to mine) you don't need any wisdom advice - if you have lasted this long then you are a survivor!
Sure ... first day is like the first day of school, all nervous and not knowing what to do - but most others are in the same position and within a few days it all seems normal and pleasant.
Good for you, walking alone - you won't be alone, you will meet so many people! - there is a basic difference between walking alone and walking with other/s ... facing inwards and outwards - alone you talk less and ponder more, alone you reach outwards whereas not alone means you reach inwards - example: alone in the evening you go to the cafe for a pilgrim meal .. if you see a table with pilgrims at it but room for another you go over and ask if you can join, even moving a chair to the table - and there you are, brand new experiences with brand new people. If you are not alone you tend to discuss where to eat, tend to take a table for two, tend to talk to each other .. this isn't judgemental, it is basic psychology.
I would offer only these
1. Ensure your return flight is far enough ahead to allow for slow days, days off, injuries, etc - the last thing you need is to set up a daily schedule and then have to keep to it - so take each day as it comes, don't even think about future days, they don't exist.
2. Switch electronics off - you can't be 'there' and still be 'at home' and every time you talk to home you cripple the once in a lifetime away from that world experience.
3. The guide books are guide books - not rule books.
4. re training programs. Are you already pretty fit or a couch potato? A lot of the Camino is very uneven and many sections are steep up and steep down (knees go on steep down). Walking around a park or pleasant home hike doesn't really cut it but what does is to load your rucksack for real then find a building with a seriously big multi floor staircase and train walking up and down stairs wearing that pack - is the nearest you can get to strengthening the right tendons, ligaments, and muscles. Though, the real problem on Camino is that you do it every day, day after day after day - so walk slow, take your time, don't book a refugio way ahead and strain to get there, just stop when tired.
5. Enjoy!
Buen Camino!!
p.s. 6. Train in the footwear you will be wearing on Camino!
p.s. 7. Many people don't train at all, they (and me) just build in really slow short days at first and maybe build up as they get fitter - they train for real on the Camino.