Did you notice how, in both examples, the drama of the event was boosted by the opening sentence? Something about the strength of those opposites gives the dramatic event more power.
- ‘Monday + sporting parents’ vs ‘Sunday + hating sport’
- ‘January + selfish + no money’ vs ‘December + changed + raised money’
When you write your opener, start at the dramatic event. Then look at some way you can introduce it with a ‘Before’ vs ‘After’ introduction that boosts the event’s drama. If you’re writing from your own experience, you may need to play with events a little to give it some punch (For example, things may not have happened Monday/Sunday or January/December, but they’re minor details).