The steeping time on this depends on how you make it. You either make it gong fu style with more tea, tell water, less time and more steepings or you make it western way.
I would suggest considering washing the tea first by throwing out the first steeping which is said to only have some colour and dust in it.
That would be 15-30 secounds at full boil or just under then throw away this and potentially doing a secound wash for a couple secounds. After the first brew increase the time based on what it tasted like (or decrease it).