I read through some animal crossing wiki, that after you have spent about 70,000-100,000 bells in the T.I.Y store that Gracie will start showing up every once a week or so. I might be so wrong about the bell amount, I'm just going off by my blurred memory xD, but what I did was just time travelled back and forth until I finished four fashion checks and slowly spent bells that reached enough for the upgrade. And for sure regular gameplay is absolutely fine, all is up to you