Not a necessity, it’s completely your choice.
Each widget can interact with the network through one app connection.
I’d have it called when the website index page is rendered in the browser.
Although, is the contact/guestbook page the only place that requires a network connection?
If so, then it might be ideal to only ask users to authorise the connection if they visit that page.
I turned contact page into a blog to make it clear I’m talking about requiring network connection on two different pages.
I just thought, ‘which two webwidgets are simplest to make that need network communication’?
Index page it is then, but that raises another question…