Rificolona is Tuesday night - the parade is from from Piazza Santa Croce to Piazza Santissima Annunziata. I am hearing it starts around 8 PM. By parade I mean a band leading the people through the streets, usually from Piazza Santa Croce, to Piazza Signoria, Piazza Duomo, and then up to Piazza Santissima Annunziata.
Tonight is the Rificolona on the Arno, where lighted boats are displayed. We somehow always manage to miss this - but I am hoping to see it this year.
Please note that the above information comes from the school system email alerts - I am the messenger here in case it is wrong :)