My impressions largely came from the Doonesbury series. Basically my impression of him was like QVC jewelry, unfashionably gaudy and showy on the surface, while being cheap underneath. Even before politics I despised him and everything he stood for.
Oh, I’ve known about him for a long time. He always personified the idea that money can’t buy you class or taste.
I was going to post this, too. 
I’ve never lived in NYC, but in the '80s, when I was in college, he was already a fairly well-known personality nationally. He was lampooned in Bloom County (and elsewhere), certainly, and known for his extravagant lifestyle, aggressive deal-making, and self-promotion, even then. The original release of Trump: The Game was in 1989, though it was apparently a flop. 
That for rich people, he (and his wives), did a hell of a lot better job raising their kids than the Hiltons and the Kardashians.
Wagner College, Staten Island, 2004
The first words of his speech were about the best piece of life advice he could give the graduates:
“Get a pre-nup”
Before the election, all I knew about him was that he was an incompetent businessman who somehow managed to go bankrupt multiple times, and that he had a humorously-bad hairpiece. He wasn’t on my radar enough to know how repulsive his personality was.
Trump always impressed me as an asshole with too much money.
He hit my radar back in the days of the USFL. I was a kid. I can’t remember if he was a team owner (New Jersey Generals?) or a founder of the league or maybe both. Always came across as PT Barnum.
Eta: http://www.nydailynews.com/sports/football/trump-defends-usfl-readies-bid-bills-article-1.1780131
When I was a kid in the 80s/90s I just knew he was a really rich guy.
When Celebrity Apprentice was on, I actually liked the show. I didn’t take it seriously and I thought Trump was pretty funny.
His affair with Maples and divorce from Ivanka was when he really dropped into my consciousness. I’m not going to go back and check the chronology, but I also dimly remember a “Loifstoiles of the Rrich and Fay-muss!” episode featuring him and whatever blonde he was married to.
Working in bookstores in the late 90s and aughts, I also remember him putting out a few shitty new books trying to cash in on the property-flipping craze exemplified by Robert “Rich Dad” Kiyosaki. “Art of the Deal” was a steady seller in mass market paperback, though. Better than the Satanic Bible, way worse than Dale Carnegie or NV Peale.
And the Apprentice shows, of course.
The Apprentice show never really hit my radar. I vaguely knew it existed, but thought in had a 2 or 3 year run. I didn’t understand that it was bigger than that. Same for Trump I guess. I knew he existed, knew about the more famous Trump properties, knew he had more money than class, and knew about the casinos. Didn’t know about the University, the steaks, or his small hands.
I figured he was a moderately liberal, and apolitical, rich New Yorker. Still do.