Reservations and pass are totally separate.

Have a look at this guide to book reservations in advance : https://www.seat61.com/interrail-and-eurail-reservations.htm

Eurail website adds 2€ fee per person per train so it's best to avoid it.

You might be too early for September depending on the route/company.

You can make reservations without activating the pass, even without buying it.

Look a carefully at the reservation costs in the link @thibcabe gave. France, Spain, Italy, and the Eurostar all have quite high reservation costs. Assume roughly €10-20 per train for a domestic journey, and €30 for an international journey.

You might consider buying tickets instead for the first part of your trip Spain > France > Italy. Consider a pass Italy > Germany > NL > Belgium. And look at cash prices on Eurostar to / from London compared with €30 each way reservation fee.

Hello,

Many thanks for your reply,

I have another question how I do to receive a Pass tickets paper???

Best regards,

Have you bought a paper pass? You should have an email from Eurail which tells you when to expect delivery.

Hello,

My trip comming soon,

Can I valid my ticket before or do I have to do the day that I will travel??

Many thank for you kindly reply,

Best regard,

Ximena

This is the information given by Eurail. 

https://www.eurail.com/en/help/already-bought-pass/how-do-i-activate-my-eurail-pass

Hello,

Many thanks for you kindly reply.

I have another question. I bought a pass for 10 destinations but I am not sure if all are include.

I will start in Septembre 23,

Rome to Florence - 1

Florence to Venice - 2 

Venice to Viena - 3

Viena to Amsterdam - 4

Amsterdam - Brussels - 5

Brussels to Bruges - 6

Bruges to London - 7

London - Paris - 8

Could you please confirm this plan is correct ??Wheater is fine I have two destination that I can use for exemple Paris-Marseille 1 and Marseille -Paris 2.

Many thanks

Best regards

Yes all these routes are included, don't worry about that. 99% of European trains are covered, only exceptions are touristy mountain peaks and so on.

Don't forget to book seat reservations whenever required. Some routes sell out earlier than others: Eurostar and night trains especially.

Have a read at

https://www.seat61.com/how-to-use-a-eurail-pass.htm

https://www.seat61.com/interrail-and-eurail-reservations.htm

Hello

You could avoid to use a day between Brussels and Bruges, you would have a day more in France or in another country for a longer trip.

Between Amsterdam and Brussels, take an Intercity train without mandatory reservation and not the Eurostar.

Kind regards

Hello,

Many thank for your reply.

Now I have another question. I try to planifie my trip at the application phone and I can see only two reservation Rome to Florence and Florence to Venice, I try many time to add the others trip and not result.

Venice to Viena 

Viena to Amsterdam 

Amsterdam to Brussels

Brussels to London

London to Paris

Paris to Marseille 

Marseille to Paris

Could you please help me,

Many thanks

Hello,

I don’t understand what do you mean. In the Rail Planner you must define a trip only to activate the pass, the days of travel and show the tickets. Seat reservations are never available in this app.

@FLORES I made a test and I had no problem to add some of your planned connections:

Hello,

We are 3 persons that we will travel together, if one of the person need to change the destination 

Is possible to book a réservation separaite ??

The projet was to travel to Brussels to London and London to Paris, but one of the person have a urgence and have to cancel London and take directly the train from Brussels to Paris, but the others two person continue the trip.

Do I can?

could you please explain me ?

many thanks for your kindly reply,

best,

Ximena

Eurostar reservations can't be cancelled, only changed. A change must be for the same route, just to another date/time.

Eurostar to/from London can be changed for a fee on www.eurostar.com via "Manage your booking”, no matter where you booked your reservation.

Eurostar Paris-Brussels can be changed free of charge before departure. Not sure if that already works via the Eurostar website. If not, then you'll need to do that where you booked the reservation.

Hello,

Many thanks for you kindly reply,

So I can do the change and we can travel separate ?? Two direction London and 1 direction Paris ??? Since the eurail pass Is one??

Best

Each person always has their own Eurail pass. If you want to travel separately, then each person needs to have their pass on their own phone.