I need Help, I got approved for Adsense from Youtube But I can't add it on blog

Hey, the one you get from YouTube (Adsense) is hosted account which can be used on google websites only, for example blogger. To add Adsense on custom domain( i.e without .blogspot.com) you need to have a non hosted account. You need to apply for that manually from the blog.

I'm tryin to add it to a blogger blog! How long does it for ads to appear?

after adding ad units

15 mins. And by blogger blog, I hope you mean: xyz.blogspot.com and not xyz.com which is hosted on blogger.

Pls have a look at my blog(link in profile). It is blogspot blog. It has been more than a day after adding ad units. But they appear as blank spaces. I don't know why is this happening.

You must have just got the first approval. Check again. 

No, i got mail that adsense is fully approved!