I took three months maternity leave and kept my nanny on full-time. If it's affordable it's a no-brainer.
DD2 and I were hospitalised a week after we left hospital due to her jaundice. No childcare issues for DD1
I spent an inordinate amount of time in the first few weeks bfing/dozing on the sofa and it would have been really stressful to have had to try to entertain my toddler and get her out to the park etc when I could barely sit down.
My nanny was v experienced but hadn't done a lot of work with very small babies. It was really good to get her back in the swing of things and spend some time with my toddler when I was up and about more and feeding was established.
I could nip to the shops for milk or have a shower with someone in the house to keep an eye on things. It was never a juggling act to get two small children dressed and in coats to just do a quick run for a missing ingredient
In the last two weeks before I went back to work, my FT nanny was on hand so I could do some KIT hours, get my haircut, find some clothes that fit, etc etc.
DD2 was early so the freezer was not filled full of all those lovely pre-made batch cooked food that MN is always on about. I did do a fair amount of casseroles etc over my 12 weeks mat leave and it was really handy to have it there when I went back to work.
Our nanny took additional unpaid weeks of holiday off at Christmas to visit family and friends. We couldn't have been that flexible if I hadn't been on mat leave. She was v pleased.
I was on Maternity Allowance rather than full pay, so 3 months was my limit so I returned to work so I could continue to pay for a nanny. It was much more important to me that I retained my excellent nanny than take additional time off and risk a childcare nightmare with a small baby and a toddler at 6 months.
IMO it's totally unreasonable to expect you to be waiting around in 3 months time.