I would begin with catching the night wees - easiest ones to catch because they're not up and around and giving confused signals At night they'll be asleep, then after a while they'll start to wriggle and maybe wake - you want to get them over a receptacle before the crying about being awake, though they may cry once you're asking them to wee in a potty. Just that this is the time they'll definitely have a wee to do.
We have achieved night continence! Wee before bed, then nothing (unless there's something else going on like teething or a cold) until morning, when I say "shishi" to her and she goes over to the potty. Shishi is what a few Asian countries use to cue for the potty, before making a 'pssss' sound - I had read that and then made a friend at Kinder who is Japanese and this is what she says to her DD My DD knows now, and if she doesn't need to she'll say "nononono", which is very cute!
So, 19 months and night continent. Day continent, too - we're in undies!