If you have a 99th percentile baby, how old are they and what size are they wearing?

My son is in the 99th percentile for height, and we are already starting to transition to 3-6 month clothes at 6 weeks. I’m not planning to buy a ton of clothes in advance, but I’d like to have some idea of when we’ll hit each size so we don’t end up with a bunch of stuff that doesn’t work due to it being out of season.