No minimum time in white
2 year min in blue
1½ year min in purple
1 year min in brown

For a total of minimum 4½ years from white to black.

Then 3, 3, 3, 5, 5, 5, 7, 7, 10 years.

I think the transition from blue to purple is quite a large one, where you need to have developed much more of your own game and a deeper understanding of the sport where you can take more responsibility for your own development and don't just copy but find new details and variations of your own on a much higher level than a white or blue belt. From white to blue is more about learning the basics and getting the general frames of reference. Of course, basic techniques too is something you'll always keep developing even as a black belt, but gaining that basics is more of simply acquiring plain knowledge. Going to purple, then you have really taken an important step in not only acquiring knowledge but building a mindset, which is the same mindset you'll refine more and more even after black. That step really needs time to mature, so I'd say two years on blue is fast even with prior martial arts or even grappling experience.

If you got from blue to purple in 16 months instead of 24, you might be disputed by some at first but it will really be water under the bridges later on as long as the total time evens out. If you're not already in the point of your development which i describe above, it's not like you wont ever get there if you got a magical purple belt placed around your waist to early. That too will even out later, so don't worry.

I should add that this is my personal views on blue to purple and might or might not have things in common with the reasoning behind the IBJJF standards.

Congratulations on your promotion!

While I can't really say why the ibjjf does anything it does, I think one of their goals is to uphold/enforce certain traditions, one of which is that, for most of us, blue belt is the toughest belt to surpass. It definitely was in my case; I spent almost 8 years (~5 active) at blue belt.

There's no minimum at white belt, as it's the, "meh, whatever" belt.

I just told you what i think about blue belt.

I think that the expectation is that one would be training, and even teaching, more as a purple/brown belt, so those belts would hypothetically go faster.

This is just my guess, but for me, personally, when I'm ranking my students, I expect them to be at blue for a hot minute. I think that 16 months at blue would be a little quick, but also not out of the realm of possibility. To date, we've promoted a total of 4 students to purple belt, and 27 (I think?) blue belts.

Damn, and I thought my 5 years was long. :D

My Professor states everyone has that one belt that just is achingly bad / slow / whatever, for him it was white, for me blue.

I'd agree that Blue seems to be the pressure cooker / crap to slog thru. Purple is certainly much more enjoyable and fun...

I got my blue belt in about 2 years, then had a struggle getting purple due to my first promoting instructor and the one that promoted me to purple having a grudge. Failed my purple belt test the first time, so 2 could set one "straight". Passed my purple belt and was there for 7 years, before I got my brown belt, mostly due to switching associations and trying to catch up to the standard my current instructor expects, 11 months and 2 weeks after brown, I received my black belt, but had to wait to register it until my year was officially up. Now, all good to go.

I went from white to purple in roughly 3.5 years. I breezed through it. I always felt like the best white belt in the room and then one of the best blue belts in the room. And then came purple. It was the longest slog and the most challenging belt by far. I was never the best purple belt in the room, and I went to many rooms. I stopped going to class for a few years and healed a few injuries, but I persevered, and a mere 9 years later, boom, I was a brown belt. I was more emotional at my brown belt than my black belt promotion. I threw out my white and blue belts long ago. I'll keep my worn-out purple belt for the rest of my life.

I think the IBJJF minimum time in each belt are quite a good guideline to follow. The only times I think I remember I've made an exception were with people who were "default" blue belts due to experience in other grappling arts. They would quite quickly get to purple. But apart from that, I don't think I've ever promoted anyone faster than IBJJF guidelines on it.

Same. We have yet to "overstep" those guidelines at my gym, but there's always a freak case, I suppose.

It’s one of the very very few things I think IBJJF get right.

Gotta give people time to quit.

Damn, that was savage