My 4 year old SS dresses himself, baths himself (I, of course, double check), washes his dishes (has his own Spiderman set), makes his bed, picks up his toys, dust his dresser, washes his walls (of which he learned to do the hard way when he got caught coloring on them), loads the dryer... I started him young as did my nana with me. So 7 is definitely not too young.
My kids started the process at 4. One is 4 now and the other is 5. They are in charge of their own messes and just recently we let them do their own showers while we kid of sit back and guide (that is a tedious learning process for some reason, maybe it's the bubbles). They've dressed themselves since 3. I don't let them do anything in the kitchen yet unless they are helping me but that's because the kitchen is *my* special room in the house. But they do clean up after their own meals. And actually this week we started having the kids clean their own bathroom (in the kid friendly sense). A big help though, for us, is that our kids are attending a Montessori school this year and they teach kids to be very self sufficient. We've learned a lot actually, about what the kids were capable of that we never dreamed of letting them do by themselves before. Like making tea. For some reason that kind of blows my mind still.
We're pushing my almost 8 y/o to be more self sufficient. In some ways, she is, but I still make her lunch and help pick out clothes and things. We've started making her pour her own drinks and cereal unless the milk jug is too full or something, then I'll help. Other things, like cleaning her own room & messes, putting away laundry and brushing her teeth and bathing herself, she already does.
At seven I can pretty well leave my kid to his own devices. He can cook, take care of his own needs, do laundry, do all housework other than vacuum, and other stuff. I suspect he could even get to the store and buy groceries alone but if course I've never tested that theory.
He doesn't do all that stuff all the time of course but he knows how to do it all. If he doesn't have school he can help me with the chores so we get done quickly and then we go have fun or if he wants to cook dinner it's good to know that he's quite capable of doing so.
What does a self sufficient 7 year old look like to you?
I don't think kids are too young to be self sufficient in age appropriate ways - so for example. My 2 year old can get himself a glass of water, grab a snack (we have fresh fruit that he can have anytime he wants on the table), and use/flush the toilet by himself. So to me, this is what a self sufficient 2 year old looks like, and I expect errors, like sometimes there is water on the floor because the water drips (we have those awful counter top things of water where you pull out the tab to use the water) or sometimes there is pee on his step stool (it happens). He just helps clean up. No biggie.
I really just think it has to do with keeping expectations realistic and appropriate for your kid. For example, IN GENERAL, I wouldn't expect a 7 year old to do all of their own laundry perfectly on their own, if at all (for me it would depend on the child. I can think of 7 year olds who would do a great job, and many 7 year olds who would need to be supervised)