Hi Delphine and Welcome to the forum, you might want to have a look at the following FAQ which explain where everything is
Welcome to Benefits and Work The relevant date is when you are being reassessed, not when your claim started. Therefore you were correct to download the latest ESA guide.
If you have problems as you are completing the form, please let us know and we will do our best to help.
You might want to bookmark/favourite this on your web browser now so that you can find it easily in future. It helps us enormously when everything relating to the same claim is kept in one place - and I hope you will find it useful too