As you are developing your site, you may want to start at a particular page for testing your web site. By defaults, when you start debugging, Visual Studio runs the page that was currently in focus in your designer.
If you set this page, Visual web Developer will start your web site with the Set Page and not the current page in designer.
You can do this by right-click on the page and selecting Set As Start Page option from the context menu.
This could also be set in Properties page under the Start Options tab as shown below.
SDET, Visual Web Developer