I went back to work a couple of weeks before Christmas, but that was just a "warm up" really, it will kick in properly on Monday 
I don't have to work financially (we could manage with DH's pay) but I like my job and I like working and tbh I really don't mind seeing a bit less of DD. (I love her to bits but am not good at spending 24/7 looking after small children!) She only sleeps 8pm till 6am (yawn) and I leave 8am and get back 7pm so I see her for 3 hours a day on work days - and when she's up in the night - and all day at the weekend. I also don't work Fridays so see her all day then. We have a fantastic nanny and I know DD is happy so no guilt.
So far so good, right? BUT (and there is always a but) I do have two problems.
One is that my job is usually a very long hours, 5+ days a week job. I'm not sure how I'm going to do it in shorter hours and 4 days. There are no role models. I expect there will be quite a lot of late evening and weekend working which is exhausting when I don't get much sleep due to Dd anyway. Less demanding jobs don't really exist in my field.
The other is that although both DH and I are working, I seem to have ended up responsible for virtually all of the house and baby related admin -morning handover to the nanny, nanny pay, arranging (minimal) social life, bloody Christmas cards and presents, buying DD clothes and kit, etc. DH and I share cooking and laundry and we have a cleaner but I can't seem to split this "wife work" with him, and it's only going to get worse when we have more DC and they are at school.
We'll see how it goes, I guess.