I have played through this game a few times and I seem to recall the Toad in question.
Y'all may be right, he may be referring to the bathroom, but maybe he's the kind of guy who just hates weddings? (Source: I'm not a fan of them myself and usually can't wait to go home--but even then, I wouldn't be as unstable as that Toad).
Raz and Raini were engaged from the time they were introduced in Mushroom Kingdom. You can explore Mushroom Kingdom before Mallow shows up and they'll talk about their upcoming wedding.
The time element of Super Mario RPG is a little unclear, but apparently the amount of time it takes you to get through Kero Sewers, the Forest, and Booster Tower (and a few other towns I'm probably forgetting offhand; it's been 4, almost 5 years since I last played this one) is enough time for those two to get married. You can sleep in the inns, but that's only one day.