Ad campaign not generating any impressions?

My listing became prime eligible yesterday, so I created an ad campaign for it. Today is the first day of the ad campaign. It says the campaign is “delivering”, but it says zero impressions and zero spend. I’m confused. Why isn’t it generating any impressions? Do I have to be patient and wait a few days? Usually, ad campaigns generate impressions immediately after they are created and “delivering,” so I’m confused here.