How to check if WebBrowser has been loading for a while?

In VB.NET, I have a windows form where I have a WebBrowser component. I am using proxies to navigate to pages and some proxies are dead/too slow so I want the program to switch to another proxy.

My question is, how can I detect if the WebBrowser has been trying to load the page for a set period of time e.g. it has been 5 seconds since it has been trying to load the page fully?

I am using HTML elements to automate the web browser btw, not sure if this is relevant information though.