Too early for earlies?

I dug some more of the ground over today and decided to bite the bullet and plant my early potatoes. I've planted a row of first earlies and a row of second earlies. I hope it's not too soon. They will be fine underground and as the ground dries and warms they should grow, but if they surface and there is a frost they could be badly set back. I haven't banked up the tubers yet so the moment a leaf appears I'll pile up soil on the row to help protect against frost and give more space to the new spuds to grow in.