DT isn't a tough position to learn so he shouldn't be that far behind. He will need to learn a little more about stunts and the zone blitzing JJ likes to run, but he should be helping very soon, especially since FSU runs a very advanced blitz scheme so he should be used to it.
As much as people say that drafting a QB in the first round is a risk DT are just as bad. You look at the last few years and you will see a lot of first round picks that have flopped.