You can but you should not do that cause for this your account may be terminated.I suggest you to put adsense account ads on your pages when you get sufficient amount of traffic.
yes you can put adsense ads in to your website if your content is unique and not low quality but its better to read the google adsense policies before applying because rejection many times can create problems.
I believe that there's a restriction in putting ads on blogs - specially the new ones. I think it should have atleast 5 posts (if I am not mistaken) to put an adsense ad