If, as you say, the pot has a drainage hole, then over watering is not really possible. Water it thoroughly each time, enough that some runs out of the bottom, then wait till the surface feels just about dry to the touch before watering again. It does look as if the soil level in the pot is slightly high, it should really be good inch below the top of the pot - this slightly too high level makes watering more difficult, because some of the water you apply may run over the edges rather than entering the soil. The pot it's currently in will only do for a few months to a year - it will need a much larger one, but eventually will suffer from being contained - these are large plants, reaching over thirty feet in height with a spread of up to about ten feet, and it can't do that in a pot.
The plant does not look like it's suffering - the browning flowers are normal, they do this as they die off. From what I can see of the leaves, they appear healthy - if the leaves start drooping, shrivelling and browning, that does indicate a problem.