@crazychemist brill, really helps.
So I would be getting them up earlier then 8am for a start, seven fifteen or 7-30 , yes it's only thirty minutes or so but it makes a difference from my experience. (These are my third and 4th babies).
They can be stretched a bit more in the Morning if you can, half an hour is not long to be awake for, I know they are adjusted but they were only 4 weeks early were they? Or was it more? Really sorry of they were a lot more premature because obviously this does effect the routine as they are still 'waking up' so to speak.
Mine were 3 weeks early so they don't adjust them, they will be 14 weeks Wednesday so imagine yours are around this age too?
They both have 4 sleeps a day currently. I would't have them having any more, and certainly not sleeping for 2 hours 5pm untill 7pm, in my personal opinion and experience that is too long this late in the day for three month old.
Any sleeps from 5pm with ours I only let them have 30 or fourth minutes. Perfect time to wake them as we can eat or do an early dinner with the other two girls who are nearly 3 and 11, then wake them for a bath which cheers them up. Just the act of picking them up and walking into the bathroom to run the taps rouses them in a civilised way without it feeling brutal!
They should be sleeping no less then three hours a day but no more then 5 really. It sounds like yours are sleeping more like 6/7 hours a day.
The buggy will always make them sleep for ages so I do wake mine if they are asleep for too long, although if they've only had thirty minutes, or an hour in their sleeps so far that day I will let them sleep for 2 hours or more.
I try and keep their total around the 4 to 4 and a half hour a day mark. That seems to be babies sweet spot for naps. Sometimes that will be one very long nap in the afternoon or late morning in the buggy , or in their cots, followed by shorter ones, or they will all be hour long naps. (Ish!)
So it is a baby lead schedule but with a but of manipulation by waking them and making sure they are awake between the sleeps for at least an hour.
Sometimes this is impossible and I'm not saying make them over tied or stimulated when they are drooling asleep on your shoulder! But a change of room or scenery helps stretch the wake up times even another ten minutes which has a huge effect over the course of a few weeks. Little by little you can really get them down to bed a lot earlier.
The goal I suppose at this stage is getting them down an hour earlier then they are to start, with the final time as maybe 7pm.
Mine are still a little off this, going down between half seven and 8 thirty.
But they too were not going to 'bed' untill 11pm/12am a few weeks ago so there is definitely a turning point in being able to tinker with their routine as well as developmentally, they will go down earlier and easier I promise.
We have ours separate at night currently, do you do both and swap nights with your partner? Have you separated them? Do they co sleep? Where do they nap?
I think it's very important to get them napping in their cots and not ALWAYS buggy or car, this can create an issue sometimes later on. It also does mean they sleep for less longer though which is a pain but it creates really good sleep associations for them, as well as they not sleeping too long in the day when they do need to be tired for the night.