Well DS was 5 so he was in school and the other two were a year apart.
I guess I coped by keeping things as simple as possible. Trips out were to the park or playgroups where I could keep an eye on them easily and I made sure that I organised around nap times so that I could whizz around the major house stuff whilst they were kipping.
It's hard though, right? I'd just suggest that you don't try to be superhuman. There'll be days when you look like you went through a hedge backwards and nothing of any merit gets done bar feeding, changing and sleeping and then there'll be days when you're all over it 
Don't forget that they're tiny people and they're incredibly bright. I did things like have the hangers for their coats down low and their boots etc in their own space so they can 'help' from an early age. This also helped post school as DS would get his kit on the pegs whilst I unzipped the small biters.
I also used reins as well as the buggy when out and about so that there could be closely supervised toddling when the chair got a bit much.
DS used to love to help too though-he was chief nappy fetcher and baby chair bouncer and played peek-a-boo far longer than I had the stomach for 
Easy dinners like shepherds pie, spag bol, fishfingers carrot and peas, omelette, 'light' curry/chilli & rice, casserole etc and eating with them all made a huge difference as they all ate much better and sat better. The biters loved garlic mash so emergency tea was always mash & something. Frozen peas are definitely your friend!
I did bath and bedtime for small biters and then bedtime for bigger DS. All usually down by 7.30.
The returning them gently to bed after tuck in method worked with all of mine as regards bedtime. We started that at just gone 12 months when they were in proper beds (admittedly I wasn't doing two at once though!).
Over all I'd say take each day as it comes and give yourself room to breathe. Trust me when I say that no-one is perfect and even the most together looking, immaculately dressed, shiny, shiny children in tow Mum has an off day or 6
