Are My Cats Kittens Developing Too Quickly?

My cat had kittens on the 1st and ive just been letting them do things as they want without thinking about it too much. Ive been handling them since they were a week old they have no problem with it and love being picked up now they purr as soon as you touch them. Today i was curious if theyre developing at the same rate as other kittens (my cat leaves them more than i think they should so theyre quite independent) but ive been reading that they dont start shakily walking around until theyre 3 weeks old but mine learned to walk at around 12 days and now (24 days old) a couple of them are running and theyre all pouncing on each others tails and exploring like crazy but i read in a couple diffent articles that they wont try to leave the kittening box until 4 weeks old. Ive cut the box low enough that they can climb in and out when they want but i have a piece of cardboard that i block the front with when im not in my room or when im sleeping. But theyve been going in and out of the box since they were 2 and a half weeks old. A couple of them are hardly ever in the box unless theyre eating or sleeping. Basically what i want to know is is it alright that theyre doing things earlier than they should be or is this bad for their joints and can cause problems later on? im worried now that theyre doing things before theyre ready

Nay, I cant imagine it will be a problem.  Some do develop a little earlier, some a little later, most along the schedule...

As long as they get good nourishment to build up these joints and structures...

But with bad food they wouldnt thrive as they do, so I think you shall just yourself happy having such healthy kittens.

Good luck!

The litter we had developed ahead just as yours are, I was so surprised. I thought I'd have a week before they'd start romping around and escaping their nest but they sure showed me that they would do what they wanted when they wanted lol. They all developed a little faster than average until it came to weaning, I let them take their time and offered them wet food mixed with kmr but didn't force it on them and they just kind of slowly started nibbling it. I think 2 of the 6 didn't even try the soft food until almost 7 weeks and hard food at almost 8 weeks lol. The best thing about that was that I never had super messy kittens to clean up as they were very careful not to stand or play in it at that point.

I guess they are kind of like children, they will be advanced in somethings and a bit behind in others. : )

Our foster cat had her kittens just the day before yours, and our experience has been the same.  These are big kittens who are doing everything ahead of the charts.  I'm thinking she was likely pretty late term when she delivered (they were large at birth).  The mama cat we have is seeming freaky about the kittens trying to get out of the box.  They've succeeded a few times, and she looks panicky, but she doesn't know how to carry them for some reason.  I'm not sure when we are supposed to make the box easier for them to get in and out of.  I read they should be introduced to the litter box at 3-4 weeks, but that would mean they needed to be able to get to it easily.  I also don't see how their mom will teach them to use the box when she doesn't seem to know how to carry them.  She tried a couple times when they were very little (when I was weighing them), but couldn't figure it out.  Are you kittens using the litter box already?