They probably didn't ship it until Monday because they wanted to make sure the ban had officially sunsetted. Probably a CYA thing, and if somehow the Wicked Witch of the West had pulled out a renewal in time by some cosmic miracle you'd have in been deep do-do if they had shipped right away. Regardless, your payment might have been send before they opened on Friday, but as far as they're concerned, they got that payment on Friday, not before. And, as I said before it really was just 1 business day (weekends don't count) until it shipped. Monday evening is still Monday (they probably only get packages picked up by FedEx, UPS, etc in the afternoon so sending it Monday morning was likely not possible). Chances are they probably handed off the package a lot earlier than 7:44PM, and that was just the time it got entered into the tracking system. Besides as busy as they likely were I'd have been surprised if they had gotten in out that Friday even without the legal aspects of sunsetting. As I said before, unless they made some promise of same day (Friday) shipment, it would really be inappropriate to give negative feedback. Neutral I could see, though I think that even that might be a touch harsh. If I were you I would leave no feedback at all.
Anyhow, your SKS will still be plenty of fun to shoot with the non-folding stock. Be grateful you're getting the stock. I can't really afford an AW at all right now, let alone accessories that are now legal again.
See y'all bright and early on Sunday! As it turns out, I'll be out in the wilds of 30B trying to figure out where the hell the mule deer are while the rest of you get to enjoy the gun show. I was going to go out there the following weekend, but my hunting partner has to go to RI on a business trip.