Plant question, when to top ?

i have a small eucalyptus plant ~6 inches tall. Wondering if its okay to top it or if i need to wait a little longer. Its shot up really fast and has a flimsy stalk so i had to stake it. Here it is a href="http://farm6.static.flickr.com/5149/5864848599_2723135c0e_b.jpg" rel="nofollow"http://farm6.static.flickr.com/5149/5864…/a anyone with experience with these types of plants any maintenance tips or suggestions would be appreciated. thx