Start with one or two posts a week eight weeks out and build to daily posts in the final week. Visibility comes from steady repetition, not one big push.
Three to five specific tags. A branded tag, a cause tag, a local tag and one broader fundraising tag outperform a long list of generic ones.
Add UTM parameters to every ticket link and ask buyers how they heard about the event at checkout. Tickets sold by source matter more than likes.