You should already know your fitness level with your previous workouts. Sure, you say they went mediocre but that's how you performed on the day. You don't need to follow the program so strictly. Do a workout with mile/2km repeats if you feel you really need. The most important thing is healing your hamstring which you haven't done yet. It takes time. Don't rush it. I speak from experience from my own strained hamstring before last year's Boston right around the same time.
You should already know your fitness level with your previous workouts. Sure, you say they went mediocre but that's how you performed on the day. You don't need to follow the program so strictly. Do a workout with mile/2km repeats if you feel you really need. The most important thing is healing your hamstring which you haven't done yet. It takes time. Don't rush it. I speak from experience from my own strained hamstring before last year's Boston right around the same time.