Mercedes just put on a video on their website talking about tires in 2018 and they said that for one of the first races there is a double step on tire selection at one of the first races.
Hypersoft is a very soft tire - i.e. Qualifying tire. Most of the races will be 2 stoppers and there will be a number of different possible strategies at each event. They indicate that for each race there will be a strategy for the front-runners, another for the mid-pack and a 3rd one for the back of the grid.
Link for the video bellow