Google Adsense take to automatically monetize a Blogspot blog: You can monetise your content with auto advertising in a simple and innovative method. With Auto advertising, you only have to put one piece of code on all of your pages.

• In around 10-20 minutes, auto advertisements will begin to appear on your pages.
• Log in to your Blogger account.
• Click the Down arrow in the top left corner.
• Select the blog where you want Auto advertising to appear.
• Click Earnings on the left menu.
• Click your current setting under 'Control how adverts are shown on your blog' 
• Select the Auto advertising option.
• Save the file.

Read More: How much time does AdSense take to place the ads?