Should be fine till Monday - Keep the must cool if you aren't pitching the yeast yet (ie refridgerator).
But if you are getting some Acid Blend, I'd recommend you get an acid test kit as well. Recipes are a guideline, not an absolute. Fruit is not 100% consistent -- one person might need 5 tsp acid blend with the particular must from their fruit, while you might need more or less for "your" fruit. Even with commercially prepared fruit base.
...and...When you ask for a good recipe for grape wine from fruit, it's going to depend on the grapes, the variety of grapes, the brix level of those grapes, the acid level .... and what sort of style wine you want out of it.
I've made wine from grapes we grow (concord x native, not vinifera) but I juice the grapes first, then add water, sugar to target SG and adjust the acid based on acid test results along with "the usual suspects" (campden, pectic enzyme, tannin powder, yeast nutrient, yeast energizer). I have recipe guidelines, but not formal recipes.
There's a nice little booklet about "making wine at home" and another with fruit wine & grape wine recipes that came with my equipment kit - from Fine Vine Wines - and I use those as my guide and reference along with help from the folks on this board.
Tell us about the grapes! There are plenty of fresh-grape winemakers here who can give you guidance for sure.
