They should be in the ground by now. Chitting is something done in January. You buy your seed potatoes and keep them in a warm dark place and they will send out shoots.
If you haven't already done so, dig the soil well and add plenty of well rotted manure. You can buy plastic sacks of manure ready to use from the garden centre. Dig trenches about a foot deep and about three feet apart, piling the soil up between them. Put the seed potatoes in the bottom of the trench and bury them with about an inch of soil. As soon as shoots appear above the ground, bury them again and keep doing that until you have used up all the heaps of soil and the ground is level.
A few years ago, they did an experiment on Gardeners World with chitted and non-chitted potatoes. The shoots appeared first on the chitted ones, but the others soon caught up and there was no difference in the yield.