I use DietPower for recording my food and exercise and their goal setter is all based on how much you want to lose and by what date. I am not sure of what type of calculator you are referring to other than doing the simple match that can be done in Excel.
I think your friends approach to some extent makes sense. All I can say is that weightloss is just not that simplistic. I wish it were as simple as setting a limit of say 1500 calories, sticking to it and being assured you will be at goal on a given date.
I have said it before but the weight will start coming off slower. Your body is going to be changing alot as you lose weight and it is far too soon to really know how your weightloss will progress. I would worry about today and take it one day at a time.
The one thing that I agree with your friend is there is no reason to set a higher calorie limit today and keep reducing it as you go. I have always gone with a more of a fixed number that I stay on throughout the diet. Not everyone agrees but it works for me.