Over the past several days, various sources reported that the match order for WrestleMania 35 underwent changes very late in the day, as AJ Styles vs. Randy Orton had been set aside as the opening match. Originally, Brock Lesnar's Universal title loss to Seth Rollins was to have gone on just prior to the main event Women's title match.
Dave Meltzer reported in this week's Wrestling Observer Newsletter that it was Heyman and Lesnar themselves that lobbied for the match to go on earlier. Though their exact reasoning is not known, Meltzer speculates that the two knew the finish would come off better earlier in the night while the crowd was still lively, as opposed to close to midnight when everyone would be burned out.
Keeping Rollins, Kofi Kingston, and Becky Lynch's big moments as far away from each other as possible, giving each their own time to shine, looks to have been the right call in the end.