The most important thing is that the chits that your seed potatoes have formed are sturdy green shoots and not straggly thin white ones. The straggly thin white ones form when the seed potatoes lack light or are too warm.
Once your potatoes start to form chits you will see that some of them produce more than others. Some people believe in is a good idea to restrict the number of chits developing on the seed potato.
I do not bother as I do not like to cut into the potato and risk spoiling it, others think the number of shoots should be restricted - mixed bag of opinions really.
If you leave less shoots you may get larger potatoes but as first earlies are new potatoes and smaller ones are nice I do not see the point. Maybe experiment by restricting the number of shoots on a few of the main crops that you will leave to develop for baked potato sized spuds.
If you are not sure about chitting potatoes here are three links with useful advice :
BBC gardenersworld video - potatoes-chitting.
How-To-Chit-Potatoes
Potato-Chits-What-Should-they-look-like
Here is a link to how to plant your seed potatoes...
BBC Gardeners World.How-to plant seed potatoes - planting.
Happy planting.
a healthy potato plant in flower
photo of potatoes in flower
home grown carrots.. grown from seed
photo of my first bunch of carrots 2009
Even a small batch of mixed fruit can be useful
Home Grown Fruit can be made into delicious compote