I live in a rural area and do occasionally see a cat of unknown ownership.
Probably two months ago I started seeing a calico cat at some wildlife
food I put out; couldn't begin to approach her.  My last cat died 1-1/2
years ago and I'd decided not to get another, primarily because it would
likely outlive me; I'm not sick, just 70.  But, being that this was a
female, I decided it was worthwhile to try to befriend her enough to get
her spayed and have a rabies shot.

I had gotten her to the place where, if I kept my distance, she would come
in an open low window to eat.  But any attempt to even touch her, she
"attacked".  She didn't appear to be either pregnant or nursing, but
obviously the semi-long-hair disguised it.

Long story somewhat shorter, when I went to the garage a week ago, the cat
cam running in and headed to a stack of empty boxes I keep for recycling.
Knew then it just a matter of how many and getting them and her into the
house.  Luckily, the four kittens weren't really walking yet and momcat
did figure out when I'd taken them and came in too.  (They're in the room
where momcat ate so it wasn't strange to her.)

The only experience I've had with kittens that young (approx 3-1/2 weeks
when found) was a similar situation years ago, but with newborns and a
trusting momcat (that the owner didn't claim). This really was just in
time. Once these kittens got out of the enclosed space they'd been in,
into a large cage (that momcat could get in/out_of) they began tottering
around. In two days, I let them out into the room.

The only fault I have with momcat is that she is too dedicated to the
kittens.  I open her window for her to take take a break outside and she
stays to keep an eye on her kittens.  The only time she seems calm is when
she is nursing them.  I am expecting that they get even more active, she
will perhaps become more distressed.  And she would be "right" to be
because my objective is that the kittens be socialized enough to be
adoptable.

As with the previous litter, these kittens seemed to learn to use the
litter box themselves.  I have seen momcat "call" the kittens to the water
dishes.  But not to the food dish(s).  She usually growls when I put the
dish down and that scares them off for a bit.  But, I have seen all but
one eating some on their own the last couple days.  Oddly, the one that
doesn't was the most advanced at walking, following a string, poking
around in the corners, etc.  At what point should I be concerned enough
about this to try to get him/her started myself?  (With the chase the
string game I am able to get them close enough to pick them up - when I'm
standing on the other side of a door gate and momcat isn't looking. <g>)

Another specific question.  Two of the kittens are more/less black and
white and two are orange and white.  One of each color pair is noticeably
rounder and has a larger head than the other.  The two larger ones were a
couple days behind on walking, but the first I saw eating on their own.
I'm guessing these two got more of the long-hair genes?

I'd like to hear other thoughts/suggestions on this.