I would just feed them now, and then in the fall, when the ferns die, remove the growth and the put a few inches of good compost on them and then a few inches of well rotted mulch. This spring, and next spring, I would just let them go strain to fern and feed them in the spring and again in summer. Repeat the compost/mulch thing every year.
If they don't come back right on schedule, wait. Sometimes I have a few that don't come up till the end of June! Yesterday, I went out to check my ferns for berries and saw 4 new large, perfect spears! It took all my will power to restrain my inner child...who was screaming for instant gratification...to keep from cutting them. I do to trust myself to go back there again for at least a week.
If they don't come up by the end of whenever your growing season is next year, they probably aren't coming up.
In the mean time, I have some questions.
What did your crowns look like when you planted them? Were the roots plump and have round tips? Was there any growth on the crowns when you got them? Were they flattened? Be real specific. Flat leathery roots on crowns are NOT a good thing, if they were like that, they PROBABLY won't grow.
How did you prepare your planting bed? Be very specific.
How did you plant them? What was your planting method, depth? What did you mulch them with?