Have you negotiated a flexible schedule or reduced your hours at work? If so, what did you have to concede?

I'm going back to work July 1st and I think my schedule is pretty impossible. I have a five minute window between when daycare opens and when i need to be on the road, and a ten minute cushion for pick up.

I'd like to ask my employer for six or seven hour days in the office with or without making up the remaining hours after LOs bedtime. I have no idea how to broach this subject with the boss. If I ask for shorter hours I assume I would take a pay cut but what amount? I think I'll end up doing the same amount of work regardless of how much time I spend in the office.

I'd love to hear how you've negotiated flexible schedules or if you asked and were denied.