Congratulations on the offer, I would take it up, esp. as sounds like the role is right for you.
I work full-time in professional services and went back to work when DS was 8 months. I did go back 4 days a week initially but that was to try it out as DH and wider family thought it might be a good idea, but found it was just a 20% paycut in practice so went back to 5 days after a couple of months.
This is how it works for us:
DS is in nice nursery nearby (or at MIL's one day a week), DH drops him off so I can start work earlier, and I pick up. DS wakes up about 6 and I leave for work by 8, DH by 9, I pick DS up by 6.30, then it's playtime, dinner, bath and bed at 8.30 for him. We eat dinner together as a family as often as we can.
My commute is 45 minutes door-to-door, DH's varies depending where he is working.
I will not work between 5.45 p.m. when I leave the office and 8.30 p.m. when DS is safely in bed but will do e-mails or e.g. conference calls with US after that. My team knows and understands this and fortunately I am senior, experienced and specialised enough to have this level of control over my workload. I have to travel for work 2 or 3 times a year.
HOWEVER, we have had a LOT of help from family e.g. DS once had to have 2 weeks off nursery due to conjunctivitis so my mum came 200 miles to stay with us and help out, and quite often my train home is late and 2 DBs or 2 DSILs and DMIL who are all nearby and all fantastic have stepped in at short notice to do the nursery pick-up run, and who are all willing to babysit for us and who are generally absolute stars whom I cannot praise enough.
We have a weekly cleaner and when the laundry piles up have sometimes used laundry delivery services. We don't do any DIY and hardly any gardening, we get a handyman in for odd jobs and a gardening service once a month. This is expensive but all cheaper than a 20% paycut so I justify that it is paid for out of my "extra" day's work each week. We do shopping for groceries and birthday presents online. We do trips to gym, bank, clothes shopping etc. either on the way in to work or at lunchtime. We wear non-iron, machine-washable clothing as much as possible!
We have very little spare time for us as a couple or for us on our own with friends as we normally dedicate weekends and holidays to family, we probably manage 1 "date" a month, 1 social night out as a couple with friends a month, and 1 or 2 nights out each on our own each month. I know the "date" thing is very important to some couples but we really enjoy our time as a family and generally get an hour or so of slobbing on the sofa together each evening so that doesn't feel too bad.
DH is freelance so has been a SAHD on and off in between contracts, which helps a lot in catching up with things and dealing with projects like moving house. On the other hand, when he is working his contracts are very much full-time and may involve being away from home for a week or two at a time, and then we get behind with lots of things again!
We're expecting another baby in a few weeks and the plan is for me to go back to work full-time when the baby is 7 or 8 months old, with the baby in the same nursery and an au pair to help with the pick ups as DS will be moving on to school nursery soon and we feel it would be unreasonable to keep relying on DBs and DSILs the way we have been, also they seem likely to start having children themselves in the next few years.
Sometimes it seems really mad and hard work but most of the time it seems manageable and worth the compromises. The most reassuring thing is that DS is happy at home and nursery and that we very much feel like a family when we are all together.