Good advice so far. I've found over the last couple of years that we (that's two of us) don't eat as many new potatoes as I thought we did, so you start lifting a row as early as you can, and then your still lifting bigger ones when the 2nd earlies are ready. Alternatively, you lift the full row because you want to plant a follow on crop, and then the spuds start to sprout in store (although I've found Charlottes don't seem too liable for that).
We seem to catch up a bit when the main crops are ready. I think you'll find there is a fair bit of trial and error before you find what suits you best - assuming you get past the slugs, drought, floods and blight of course! Happy gardening!