AIBU to not agree to 50/50 custody?

Worth considering that if your ex has recently got legal advise, he may be now pushing for 50/50 so he doesn't have to pay any CMS.
That's what happened to my colleague when she went through a divorce, ex wasn't interested in having the child except EOW and then got advice from his uncle who'd also recently divorced who told him to insist on 50/50 so he didn't have to pay CMS. Its ended up with a convoluted schedule in which the mothers of my colleague & her ex are having to step in to help with the pick ups/drops offs/handovers because both my colleague & the ex work and the schedule he insisted on to ensure 50/50 was also concocted to mean her had the least amount of time actually looking after his child. He does mid week rather than weekends and has his mum do school pick up/drop offs so he only sees his child to put her to bed in the evenings in the week.

What kind of pattern is he asking for ?

You made a child with this man. Of course he deserves to have 50/50 as long as he can accommodate it and that bit is on him.

Your DC is still very young so will have plenty of time to get accustomed to the setup.

Kindly, it seems to be a lot of back and forth/…

do you think for example your ex might agree to have DS Thursday evening to Saturday evening (maybe drop him back for dinner/bath bed routine etc).

m that way he still has him two nights but has two full days with him instead so might feel he has more time do thing with him etc.
you also get two full days and the other nights (and his days at nursery/ with your mum)
do you think that could work?

How would you feel if you would only see your baby a fraction of the time?
that is probably how he feels.

This man is the other parent to your baby. He should be able to be an equal parent and 50/50 isn’t unreasonable.

Could you suggest starting the 50/50 when.dc turns a year old?Most courts would agree with you on the 1 year of age. Also if you have Monday off and Thursday your Mum looks after him you could suggest you also have Saturday, offer him Tuesday, Wednesday and Friday and alternate on Sundays. Then he'll either have to look after him himself or pay for him to go to nursery on Tuesday and Wednesday. That way you wouldn't be responsible for any nursery fees. But make it clear you will only agree to this once DC is a year old.

I do get what you are saying and like PP said I don't think 50/50 is always in child's best interests. It can be unsettling and disruptive.
Is he trying to avoid maintenance?
I would listen to advice from your solicitor - you have a lot to process at the moment including returning to work and moving house. Your ex doesn't have these additional stresses.
So try not to feel pressured to agree to something immediately.
Do you think he is trying to scupper your mum having DC on Thursday ?
Would you having baby Sunday to weds lunchtime and him having baby weds lunchtime to Saturday be feasible?
Could child care be swapped round at all so you mum had DC Tues or Weds and they are at nursery Tues or weds and Thurs?
But I think you saying DC is to young for 50/50 at present but will review when they are 2 is reasonable.

But presumably you don’t agree with 50/50 because you’re assuming you’d be the “main parent.” What if he was proposing that you only had DS for the time you’re suggesting he should have him? Surely that would be equally fair? Why are you assuming that you’d automatically be the “main parent?”

There's no such thing as a right to time with your child let alone a right to equal time. There is equal parental responsibility which is not the same thing at all. Child arrangements are about doing the best thing for the child and anyone who's looking at it from any other angle should take long hard look at what they're advocating. It is highly unlikely it is in the best interests of your 9 month old to have 50/50. Provided he isnt abusive it would be reasonable to work towards that over time. If he's not abusive it might be worth doing mediation with him.

What is he proposing in terms of which days does he think he can do 50/50, as if he is only wanting to include every weekend, then it won’t be fair on you. He has DC 2 nights a week now, personally I think that’s enough for a 9 month old. If you cannot agree, maybe going to Court to get a schedule mutually agreed would be best.

As a person who thinks dragging a child of any ages back and forth to different houses doesn’t have their child’s best interest at heart. Egos is all it is.

It’s difficult op. He has every right to be an equal parent, and unless there is additional needs you’ve not said. A court will go for equal custody if both parents are able.

How does your mother cope if she has him all day on a Thursday and he only settles for you?

He is the childs father at the end of the day. He has equal responsibility as you do, and the child deserves an equal relationship with his dad.

I get this OP. You feel 9m is too young and maybe it is. Have you suggested a different start date? E.g. “I’m not comfortable with this when DS is so young, but I would be comfortable starting 50/50 when he is 18m/2yo/3yo and better able to understand what’s happening.” You ex might be suspicious that you’re trying to keep DS forever and using age as an excuse, but if you give a clear end date then perhaps he’ll be more understanding.

I'll probably get flamed for this - but I don't think 50-50 is good for children at all and even more so if they're under secondary age.