i believe you wouldnt rush her, but 4 yrs is a long time to wait.
And even if you werent in a rush, its not to say she isnt.
If you really wanna date her, wait 2 years when shes reached more maturity (aint saying shes not mature, but give some time for her to get things in view), then date her. That way you wont wait as long till shes a legitimate age.
4yrs IMO isnt an issue. Heck theres a 15 yr gap between my parents. I dont find it gross, or unacceptable at all. But when underage laws come into play its a area worth thinking about (im not talking about the physical side of a relationshiop, but societys view on a nonphysical relationship between an underage and an adult), which i think leafs is doing the right thing about it.