I'm only an expert because I've done everything wrong possible but I have to say that nothing with credit moves any where near as fast as you want it. 6 months Im afraid is a tall order to build credit history.
You need to look like someone who is trustworthy and lives within their means, this person however rarely needs credit...
Easiest answer, find some one with great credit and convince them to love you and then use theirs, thats what I did