Here's the Start Simple kit of waxes that will get great results without making things too complicated.
Base Wax: LF10 Green or BWLF
Main Glider: HF6 Purple
Fluoro: HF11 Block; soft enough to crayon-on thick enough to iron it for durability
Base Kick: Base Extra
Main Kick: Oslo Purple
Additional Kick Waxes if Forecast Changes Slightly: Uni Wide Klister, Oslo Blue, RF Red, RF Purple
For glide waxes, I tested 4 base waxes yesterday, with START BWLF (Base Wax Low Fluor) and START LF10 Green being the best 2. BWG (Base Wax Graphite) was really slippery feeling at slow speed, but was definitely slower at higher speed. BM6 which is usually my "go-to" for artificial snow, was OK, but not as good as either of the top 2 in slow or high speed glide.
Based on the forecast for the rest of the week, I'd be pretty comfortable recommending START BWLF as the base layer at least for Saturday, Sunday and Monday's races.
For kick wax, I'm guessing a little, but based on how the snow at Wirth usually acts, and what the forecast looks like for Saturday, it could be Base Extra ironed, Oslo Purple, final layer FHF60 Red (or FHF40 Purple for later starters). If it trends a little colder, maybe Oslo Blue. Generally speaking, the Oslo line is almost always in the mix at Wirth, even on the natural snow because of the layer of ice under the natural snow which gets exposed because it's often pretty windy at Wirth.
I hope that helps guide your selection a little. Finn Sisu (about 5 miles from Wirth), Hoigaards (about 10 min from Wirth), Pioneer Midwest, Gear West, and Boulder Nordic (each about 25 min from Wirth) have Start Wax in stock, too.