I just received an order of plants (Wisteria, Sprite, Java fern and Anubia
nanas) but the Flourite won't arrive for another week. Is it ok to just
let
them float around for a week and plant them after the Flourite gets here
or
do I need to plant them now and uproot and replant later?

Java fern and Anubias dont need substrate. They need support. You can place
them on a driftwood or on a rock. If you have got some other substrate just
go ahead and plant Wisteria and Sprite. They'll grow everywhere.

Dominic