It depends on his tolerance for noise, whether he has to vocally interact or quietly plug away, and the soundproofness of his office.
I work part time from home, and so does my husband. We have two school-aged kids who are homeschooling, so our small apartment becomes a co-working space during the day. (We don't have offices.) We do have coffee shops and libraries within walking/biking distance, and we can work more efficiently while away from home. With our lifestyle, it's not hard to coordinate and schedule blocks of time in which one or the other of us can get away.
We're always right on the edge of joining an actual co-working space. In our area one can get access to "float" at an available desk for $175 per month, or a private office starting at $275/month. These co-working spaces include gym access, free coffee, fast wifi, access to conference rooms, and networking opportunities / getting to be around fellow entrepreneurial types. Tempting!
Other things that we've found helpful:
- Babywearing can be a great way to keep your baby quieter and happier while you do housework and keep your older child engaged. (With many additional benefits for you and your baby.) Don't give up if your first attempts with your baby carrier don't go well. Be willing to try a different carrier. Many cities have babywearing groups or even free baby carrier lending libraries so you can get help from experienced people and try out different carriers that might work for you. I would recommend against Baby Bjorn. Try a ring sling and a structured carrier like Ergo. (I apologize for the unsolicited advice! YMMV)
- Do you have a nice neighborhood 10-year-old girl who wants a little extra cash or some kind of lessons you could provide? Hiring a mother's helper for a few hours here and there to play with your older child could be a real sanity saver. (And an enriching experience for your child.)
- Find out-of-the-house things to do that aren't expensive and are newborn-friendly. Do you have friends or family you could drop in on? It's nice to have a few ideas in your back pocket for times when you and the kids get restless or your husband will need assured quiet. A good baby carrier can really help with this - you can take your older child to the playground or on nature walks while the baby stays happy, and you're not stuck pushing a huge, ridiculous stroller (which to me, feels like a barrier to interacting with your older child.)
- You might want to plan an hour or two in the evenings where your husband takes over so you get a moment to yourself and don't feel like you're constantly "on duty." Keeping kids quiet during the day does take some additional effort.
- Be mindful about the kind of culture you want in your home. Read to your kids so they can learn the quiet pleasures of reading. Don't let them watch shows where the characters are loud and obnoxious and disrespectful.
- Incorporating some Montessori ideas into your home might help things run more quietly. When kids' stuff is well organized on open shelves, it's easier for them to find something constructive to do. (It also becomes possible for them to put away their stuff afterward! Not likely, but possible!) Kids love to do things that feel like real work. Don't expect perfection and give them the right tools. A child can get really interested in sweeping or dusting along with you, folding laundry, cutting cucumbers with a butter knife... get creative about ways they can help!
Also, remind yourselves what a blessing it is to eliminate commute time from your lives and have more time to spend together! Staying positive and thankful will give you the motivation to find solutions to the difficulties.
I'm cringing at myself for giving so much unsolicited parenting advice... but I do think it matters. When it comes to working from home, your parenting style will have a bigger impact on how well it goes than the size of your house.