You could...and I did mine yesterday.
I think of it this way...they've stood on that same ground for looooong time used up lot of goodness + all that rain over the winter, there can't be huge amount nutrients available for them..and little bit of feel will help the plant to produce florets with more 'omf'...rather than skinny little weedy things.
Oh it is so nice to see first crop of the season coming on...won't be long now...