when should i plant my potatoes

Still chitting ours at the moment, first earlies and maincrop.
I think it can be confusing sometimes when to plant things. I've ordered a lot of seeds etc ready for the year and the majority of the instructions say to plant in February/March, but then some people suggest leaving later till the soil warms up.
Last year we got everything started a little late as we had just moved house, most went in end of April beginning of May but still got results. Just want to make the most of the season this time!