LOL that is soooooo Venuto...
That should do... if you are only starting, you may need to do 1 min hard, 2 min soft (to catch your breath), this only until you have the stamina to do the 1 min, 1 min...
I do normally 2 min, 2 min (but my cardi is not strictly HIIT: I do it for 45 min, and my high is 88%-90% and my low is 75-80%.
I guess the best advice I can give is: LISTEN TO YOUR HEART... go get yourself a heart rate monitor.