Question about feeding times

I have two older cats, brother and sister who are a year and a half. I put food down for them around 8pm and take it up at 8am the next morning, so basically they free feed through the night. We recently got a kitten, I keep her food down all the time. She is now about 7 weeks old  and I was wondering when I can start feeding her just at night like I do my older ones?

Most sources say cats are generally done growing around 1 year old, so by that point you can meal feed her too. I've seen some sources say to taper off around 6 months and introduce meal feeding, but still make sure she's getting plenty of food because at 6 months cats still have lots of growing to do.

While I feed my kitten (4.5 months old) twice a day, I'd say you could go ahead and do it now but I would personally add in a "meal" (Preferably some canned food) between those hours. Say around 2-3ish if possible since it may be odd at first for the kittens stomach to adjust to 12 hours of food and then a 12 hour fast. I'd say give it a few months before switching to just nighttime feedings. Jm2c.