Social media reaches people who follow you. Search reaches people who do not know you exist but are actively looking for something to do this weekend. That second group is larger and warmer than most organizers realise.
Title the page the way people search
Not "Vol. 4" but "Live Jazz Night in Victoria Island, Lagos". The event's clever name means something to your existing audience and nothing to a search engine or a newcomer.
Include the city and the category
Most event searches are local and categorical: "comedy show Lagos", "tech conference Abuja", "things to do in Lekki this weekend". If those words do not appear naturally on the page, you cannot appear in those results.
Use structured data
Event markup lets search engines show the date, venue and price directly in results. It is one of the few technical SEO changes with a visible, immediate effect on click-through.
Write a real meta description
It is the advert for your link. One sentence about the experience, one about the practical detail, under about 155 characters so it is not cut off.
Publish early and leave it up
A page published six weeks out has time to be indexed. A page taken down the day after the event throws away the authority it earned; leave it up with a link to the next one.