All good advice here. But black will start to show swirls over time, it's inevitable and why you do a polish 1-2 times per year. Considering your car is so new, the swirls you might be noticing may have been there from the dealer or factory. Dealers commonly use filling glaze to make the paint look pristine when you take delivery, but after a few washes it wears off and the true condition of the paint is revealed.
Don't think for a second the paint on a new car is perfect. That's far from the truth.
'15 i3 REX // Capparis // ZGW // ZTD // HK // 20"
20% Tint, Coding, LED High Beams/Signals, Painted Reflectors, MAX2 Hardwire
Past: F30 335i, E90 328xi