It'd have to be the 180k reputation milestone.
At that point, you get 90 bonus flags for the maximum of 100 moderator flags each day, regardless of your internal flag weight. However, if you flag perfectly and have hundreds of helpful flags, you'll reach the maximum sooner — 10 default, 32 from flag weight, 58 from reputation means you'll get 100 mod flags at 116k reputation.
Maxing out your delete votes happens a lot sooner than that even: 30 votes at 35k reputation.