We plant ours initially to cover the potato plus about 2 inches, after the roots are approx 1 inch or so, when a green shoot appears above te soil cover it, keep doing it , carefully don’t knock the leaves off, you will end up with a ridge about 8 inches high, ours are in tubs, so no ridge, we just cover it level, we then leave ours until after flowering.
There are many videos on YouTube , some people put them in a container and fill it with soil immediately, but I’ve not seen what crop, if any, they get.my Mum used to plant some in September and had some at Christmas, but she lived near the coast so warmer than us so I haven’t tried it yet.