I was supposed to be doing turmeric starting last October, to go into my tiny hoophouse in June, for harvest in Sept-October. It takes about 10 months to grow, I've read. But....
If it's at all like ginger, you wait until the foliage is pretty tall (my ginger got to 3' - 4' tall) and starting to turn brown.
I think.it might be. I want to try ginger too! Were you planning pots or does it go straight in the soil? If I can do a row of pots I can get more in there...
I started it in huge pots, then put it in the soil in June when it was warm enough.