when to switch to convertible car seat?

Maggie
My little one is 28 inches and the max on her infant seat is 32.  She still has a way to hit the weight requirement.   But she is getting heavy along with the weight of the car seat.  We have the Graco 4ever Extend2Fit 4 in 1?  Has anyone switched to a convertible car seat yet?  If not, when do you plan to?