Depends what sort of student you're marketing to. College isn't like high school where they enter at 8am and leave at 3pm with everyone funneling through a single chokepoint.
At the college level there's a steady stream coming in and out, usually from multiple entrances and exits, so you have to decide the sort of student you want to target. Do you want to target the morning person, or do you want to target the person who stays up all night? You might go for the morning person if your product is about ambition, self-improvement, etc. but you'd go for the night owl if you're trying to market a video game or sell pizza.
Once you know the sort of student, now you figure out what financial status you want to target. This is so you can place yourself at the appropriate entrance or exit. Generally, there's going to be multiple parking lots, and you can target the location that has the appropriate financial status. Same goes for any dorm rooms, as students of similar financial means will usually stick together. This is why you'll see all the beater cars in a particular lot, and the kids with the Bentleys and Porsches are in a different lot.
And keep in mind that some people, like myself, will purposely never purchase anything from you if I'm handed a flier at the wrong moment. If I'm walking by with a purpose and you stop me, or you interrupt a conversation I'm having with someone, you can bet I'll remember what you handed me. But it won't be for the right reason.
If you want to market things you need to think about all these aspects and more. It's not as simple as morning or night for better results; I mean if that were the case then everyone would market at a certain time and you wouldn't even have this question. Your marketing 101 class would be like "always market at 4pm for best results".