must i have a site before i can connect my blog with adsense

 Yes, you need to have your own website or blog to connect it with AdSense. AdSense is a program that allows website owners to earn money by displaying ads on their sites. You cannot sign up for AdSense without having a website or blog that you own and control. 

Here's a more detailed explanation:

• AdSense is website-based:

  AdSense is designed to work with websites, so you need to own or have control over a website to display ads. 
• Website ownership:

  You must own the website or blog you want to connect to AdSense and have the ability to edit its HTML source code. 
• AdSense policies:

  Your website must comply with Google's AdSense program policies and guidelines. 
• Adding your site:

  If you haven't added your website when you created your AdSense account, you'll need to add it to the "Sites" section in your AdSense account. 
• Verification process:

  Google will verify that you own the site and that it complies with their policies. 
• Blogger exception:

  For Blogger blogs, you can connect your blog to AdSense through the Blogger dashboard.