[blindmute]

My reasoning is that the coffee will cool in a curve having high rate of temperature change at first, and slower later in a long tail until it reaches room temp. Adding the cream will "remove" a fixed amount of "heat units". The heat of the cup can be graphed as heat/time and it will look like exponential decay.

If you remove those units at the start, you've reduced the starting temp a bit, but you haven't much changed the long tail of the cooling. You essentially just started the coffee at a slightly cooler temperature, but this doesn't affect the curve much. Or to think of it another way, the change in temperature at the start corresponds to a small amount of X axis (time) on the curve.

If you add the cream later, the temperature reduction corresponds to a larger amount of time on the curve. This means the temperature will be lower than the above.

So to my intuition, cream first should yield hotter coffee