Who knows if that is actual the case here but I don't think the delayed filing is all that out of the ordinary.
Attorney of over 20 years here. As some other posters have indicated, you are right. It's extremely common to wait until the last minute ("last minute" defined with reference to the applicable statite of limitations). Timing makes no difference: courts don't put a smiley sticker on your summons and give you extra credit, let alone view the case with a less critical eye, for filing suit on the first possible day instead of the last.
Lawsuits are, and should be, a last resort. Parties will typically try to negotiate first, which can be a lengthy process. Plus, in the case of personal injuries, it can make sense to wait if you're the plaintiff, to make sure that any administrative investigations related to your injury are complete, all the ways you've been injured have been diagnosed, all the long-term effects have been identified and taken into account, and all the out-of-pocket expenses have been documented (and future ones can be estimated with reasonable certainty). While you can always add such things to the case later, you're in a better bargaining position to settle the case quickly (which is often the real goal and the best possible outcome for everyone) if you have that information at the outset.
On a personal note, if the condition of my vagina and bowels were about to become national news, with an army of Disney lawyers and publicists and a callous American public primed to scrutinize, mock, and trivialize my body, my reputation, and my case before a single piece of evidence had even been presented, you can bet I'd wait until the last possible second to file, after all other avenues had been exhausted, and after I'd had sufficient time to prepare myself and my family, mentally, for what was to come.