LOL ... It didn’t take you long to gauge the level of my culinary expertise. I could give you an even more accurate gauge than saying “a box of macaroni and cheese”, etc., but I think I will let your understanding rest where it is.
Do I gather reasonably correctly that you would make a soup type dish with the celeriac, or are you looking more for a “mashed potato” type concoction? I know that celeriac is long-lasting, so I don’t feel under time pressure to use this immediately.
That's just me. My daughter's mother-in-law would disagree (loudly, in Cambodian) but I'm a French bastardizing classicist by nature, history, and training.
Escoffier does list a recipe (955) for Celeri-rave as an Hors-D'oeuvre. Julienne and mix with mustard and cream sauce (207) or a mustard flavored Sauce Vinaigrette.
I'd save a bit to try in that method, just to see.
/johnny