Reservations are optional in Germany and in most European countries. With Eurail you've got maximum flexibility : simply take the first train you're able to. Log it on Rail Planner app, hop on and find a seat.

This wouldn't work in France and Spain with mandatory reservations on fast/high-speed trains though.

Thank you 

I will have 1st class  GP eurail for going to Germany , Switzerland and Austria.     I would like to be in the 1st class carriages.     As you say it sounds like if I LOL have time to catch the earlier train.   I would need to log into my planner ( which I read is slow) before boarding.     I read where using OBB would be faster to book train.    Tho they stop accepting bookings close to departure times.

oh boy.     Sorry 

You need to change the train in the Eurail app. But this doesn’t ‘book’ anything. It just logs which train you took. You can even do this after departure if necessary, there’s no deadline. 
 

a seat reservation on these trains is optional. 

So there are 2 things here :

Rail Planner app : you have to use it to log each train you'd like to take. It'll give you a QR code (your ticket) which you need to show to staff.

ÖBB and other places : you can make seat reservations there. These are on top of your pass : sometimes they're required, optional or don't exist at all.

ÖBB can issue free reservations for 1st class passholders in Germany, Austria, Czechia,... You're able to get reservations at all times, maybe until about 5 min prior to departure but I'm not even sure there's that limitation.

In any case you're always allowed to board trains without mandatory reservations. Even on busy trains you should always find a seat (esp. in 1st class).

If you're worried make reservations for 2 trains you might be able to take. They're free so... If the seat is unoccupied after 15 min, someone will sit there anyway so you don't have to feel bad about it imho.

Thank you both,   Great information.

Now. Have the scoop.

i am thankful to be part of the eurail community .

you guys/gals are the best