It depends on the keyword you are going for.
If you know your keyword, just type it in google and it will give you the results. Then you can easily see where you are..
Be aware that if you are logged into google and have been to your site a few times, your site will pop up towards the top because google remembers which sites you like... So, clear cookies and log off of google before searching...
If you dont know the keyword you want... then keep reading..
The first thing you should do when you are starting a hub is target a keyword you know people are searching for. Use the google keyword tool and it will tell you how many people are searching for this term.
You want to target a keyword like "pirate birthday party costumes" or something that is specific, not a general term like "costumes", because you will never make it to the top (well, you could, but it will take a long time and a lot of work).
Then build your hub centered around that term, and others like it..
to improve your rankings, build backlinks!!! join some forums with dofollow signatures, shetoldme, and any other sites which allow you to post your site... there is lots of info on link building.. just don't pay for any..