I made a batch by hand for an afternoon party I was hosting — soaking the juice in the zest overnight, etc. — and when I ran out, I subbed this in, and really couldn't tell the difference 🙃
In some states, TJ's can't sell booze and can't/won't sell mixers. I haven't tried it personally, but I've heard that "Simply Limeade" is a good substitute. (I've also seen a lot of people use TJ's Jalapeño Limeade, but that's not my jam).
If you don't have any of these options, here's the America's Test Kitchen margarita mix recipe to make ahead:
Combine lime zest & juice, lemon zest & juice, sugar, and salt in large liquid measuring cup; cover with plastic wrap & refrigerate until flavors meld, 4-24 hours.
Divide 1 cup crushed ice between 4 or 6 margarita or double old-fashioned glasses. Strain juice mixture into 1-quart pitcher or cocktail shaker.
Add tequila, Triple Sec, and remaining crushed ice; stir or shake until thoroughly combined and chilled, 20-60 seconds. Strain into ice-filled glasses; serve immediately.
Pretty sure no one really needs a cocktail stirring spoon, but if you want one, this one has the appeal of being a bit like a magic wand...