A.M.
We've just recently gone through this struggle and won the battle! Finally! My son is 3 1/2 and I've been doing this for what seems like a year -- off and on. But I would see some signs that he just wasn't ready for it yet. Like when he would have an accident - he felt no shame or remorse. It didn't matter that I told him that I was dissappointed in him --- he just went on playing like nothing ever happened. So that told me that he wasn't ready -- so i'd back off and wait patiently and start again in a month.
I would say that even though your kids aren't letting you know when they need to go yet....just initiate it by telling them it's time to go (not asking)...and time it every hour ...and then space it out the next day ...every 2 hrs. etc. Soon, they'll get the hang of it and they'll be tired of mommy telling them when to go....they'll get independence and tell you when they need to go. Or what my son does now...he just goes in the bathroom himself without announcing it or needing my help.
I also started communicating with him, after a trip to the potty, that he needs to keep his pants dry (I'd have him repeat what I said so I know he heard me)...and that he needs to hold his pee-pee and poo-poo until the next potty time. Because, if you think about it, they've really had to "hold it" and that concept is foreign to them. There were some accidents that had to happen....I think they need to feel what an accident is...and see the mess they make on their favorite Batman costume or whatever they like --- "oh no...now you can't wear Batman anymore because there's peepee on it...we need to wash it. But you'll have to wear something else now."
And see the dissappointment in my face and tone when an accident happened.
But when he kept his pants dry at the next potty time...I showered him with hugs, kisses and tickles. We even rewarded his first bowel movement on the potty with a trip to Chuck E. Cheese. And we kept telling him why we were there...and what he did to earn this outing. It really left an impression on him.
So keep at it....just keep initiating and telling them it's time to go to the potty. You have to do this first before they pick up the idea that "hey...I can hold it...and be a big boy/girl and tell her when I need to go/or go when I decide it's time to go." It's a process. I've heard of some doing it in a day...but I've never meet any of those people! maybe it's an urban legend. :-)