potatoes how long to grow?

Some say just as they flower, some say when theyve finished. Have a careful dig around the plant to see the size that they are. Normally when they are in flower, they do like a good drink to 'plump up' the tubers. If they are new spuds then you want them small.

when should i plant seed spuds to harvest new potatoes for chritmas dinner. Thanks

Now is the best time, or stagger it to get longer harvest