Hi T.,
I'm sorry I won't be able to answer your question directly, as I really don't have a real routine! My kids are 20 months apart; my son is 3 and my daughter is 21 months. Life is CRAZY around here so I understand your question and I myself wonder if things would be better if I had a routine. (I've tried, but things just don't "stick", and like someone else said, routine with a 4-week old might be pretty hard!)
I also agree with the person who said that pretty much stick to just doing laundry and dishes. I am the exact same way! With dishes, I make sure to (or at least try to) empty the dishwasher first thing in the morning, and then I load it throughout the day as I go. I also use many paper plates and paper bowls (at least for myself) to make sure there is enough room for everything in the dishwasher so I don't have to wash anything by hand, except an occasional item that is not dishasher safe. Then I run the dishwasher every single night, and I admit there might be a time or two per week when it is not completely full but I run it anyway. I feel bad for wasting water but until my life becomes less chaotic, my first concert is saving my sanity through convenience!
Laundry is another thing I stay on top of..sort of. I do run at least one load every day, but many times at least twice a day. I do not separate my clothes by color and I've NEVER had a problem with colors bleeding. If I buy something new that is bright blue or bright red or whatever, I will wash that item separately but for the first time only, just to be safe. So I wash all my "normal" clothes in cold water, but I wash socks & underwear separately in hot water, as well as dishes and linens. I just feel "cleaner" if I wash the underwear in hot water, not really sure if there is anything to it. And the only reason I wash the socks with the underwear is because it's easier for me to sort once they come out of the dryer!
In my laundry room, I have separate laundry baskets. I have one for my son's clothes, one for my daughter's clothes, one for our towels (and sheets, if need be), and one for clothes belonging to my husband and I, clothes that do not need to be hung up (or at least the ones I don't care if they are wrinkled: socks & underwesr, sweat pants, pajamas, gym shorts, etc.) I try to put our clothes away in the bedrooms often, but when that just doesn't happen, it's easy to find the things we need in their designated laundry baskets. Right away, I hang up the items I don't want wrinkled, like nice tops / shirts and pants, and I hang them on this over-the-door rack I have on my laundry room door. It's got 6 "pegs" that I can put my hangers on. I rarely EVER iron, since nothing gets wrinkled if I hang it up right away. If something happens and I need to "de-wrinkle" something, 99% of our clothes can be "de-wrinkled" just by throwing it in the dryer for 5 minutes or so with a damp wash cloth, on at least medium heat. I hate ironing!
I have 3 bathrooms, and under the cabinet in each bathroom I keep one container of pre-moistened Windex wipes and one container of the Clorox or Lysol wipes. This way, I can clean my bathroom super-duper quick, even if it's just "spot" cleaning. I also like to do this when my kids are in the tub, I just take 2 minutes and make the bathroom look clean.
Don't worry about your house being messy--I've always felt it is WAY more important to hang out with your kids! They grow up way too fast, as you can see by your 8 year old! And you don't always have to have something structured to do with them; just hanging out being there counts! Lately I've been folding towels in the living room while my kids watch tv, and they seem so happy just to have me sitting there! But honestly, I only fold the towels if I have a huge mountain of clean towels that need to be put away; otherwise, if it's just a "small" mountain, I ignore the towels and just sit on the couch with my kids while they watch tv, because then it's easier for them to sit on my lap or hold my hand, etc.
Back to just hanging out with your kids, especially the 15 month old. Kids learn through play, so as long as you are doing ANYTHING with them, they will learn. Peek-a-boo, hide and seek, rolling a ball along the floor, using a flashlight to make the light "dance" on the wall, etc. You can do simple projects with your son, like finger painting or playing with cooked spaghetti noodles (or combining the two!) But I wouldn't worry too much about art projects yet. You can also just pop in a kids cd and do silly dances--kids LOVE that!
And personally, I find nothing wrong with popping in a video for your 15 month old while you tend to the baby or make dinner. The videos my kids loved at that age were by Nickelodean, called Curious Buddies. I don't know if you've ever seen the show called Jack's Big Music Show on Noggin, but the puppets are basically the same (and it was created by the same people.) There are a few different videos, but they combine puppet animals with real kids, and they sing songs and show kids doing things like playing in the park or on the farm, etc. I ordered mine online from half.com (cheaper that way), but you might be able to find them at amazon.com or whatever. Our favorites were Curious Buddies at the Park and Curious Buddies on the Farm and Curious Buddies Let's Move (that's an exercise and dance video.) Those were the only videos my kids were really interested in at 15 months and they really did help me make dinner or whatever!
Speaking of making dinner, I find it easy to make crock pot meals, OR, I can prepare a casserole dish while my daughter is napping in the afternoon (my 3 year old no longer naps.) I put all the ingredients in the casserole dish and then either cook it right way (and then refrigerate it and re-heat it when its time to eat), OR, I put it in the fridge uncooked, and then heat it up an hour before it's time to eat. I usually opt for cooking it right away and then re-heating it. I figure, it's easier to just cook while my daughter is napping since I have to stay inside anyway, and once she is up, I'd rather go somewhere or play outside when the weather is nice!
I hope I was able to give you a few helpful tips. Just focus on spending time with the kids and clean only when absolutely necessary! Good luck!
D.