Starlit Kart Racing

At the time of writing this, I've completed 26 races, as I found by adding up the number of 150cc and 300cc races I did from their corresponding 100 race completion achievements. This has put me at 37% on this achievement's tracker. So based on this, you should be getting 1-2% worth of progress towards this achievement, depending on how many star boosters you hit, per each cup race (3-laps each). If you've completed all of the cups and still don't have this achievement, then you can replay the old cups and progress will still count. So based on this rate of progress from playing the game normally, it should take at most 70 races for you to unlock this achievement. But if you simply target this one by making sure to hit every star booster in each race, you should have it sooner.