On Friday. We use "in" with times of day, always with "the". In the evening. When we say "(preposition) Friday evening", the preposition we need is "on" because the main noun here is Friday, not evening. We can think of the noun "evening" as acting like an adjective, post-modifying "Friday". More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.